What to do to make it work
This summarizes installation quickly.
If you are relatively new to X-Plane plugin installation and/or especially to CSL model installation you definitely want to follow detailed step-by-step instructions instead:

Limitations and Requirements

First of all make sure to understand inherent limitations of the approach LiveTraffic takes and if it fits your purpose under these conditions. Then please double-check requirements are met. They include
  • Windows: required redistributables (download)
  • MacOS: Tips for security prompt issues (FAQ)
Windows only: Do update the Visual C++ Redistributable!
As it seems that various hints to verify requirements (like above) aren't sufficient here once again in a hopefully visisble way:
Otherwise, LiveTraffic might not start and might not be available in the plugin menu. In Log.txt you'll see Error Code = 126 : The specified module could not be found.

LiveTraffic plugin

Download the plugin from
The LiveTraffic plugin ships as a ZIP archive. Unzip it. The LiveTraffic folder is then to be moved into <X-Plane>/Resources/plugins, the same as with other plugins.

CSL Packages

You must install CSL packages with aircraft models, otherwise aircraft models are restricted to what X-Plane has loaded in terms of .acf models (including AI)...not too many, often even none and then you see just labels but no aircraft.
To start with please use the Bluebell packages. They are known to work. Users experienced with CSLs might venture father.
The Python script CSL2XSB can try to convert other packages for use in LiveTraffic. It has been developed and tuned for X-CSL but may work for other packages, too, to a certain extend. Feedback welcome, e.g. as comments to the file download.

Bluebell OBJ8 CSL packages

Install "Bluebell" OBJ8 CSL packages (or, recommended, take this ZIP file version) including the vertical offset files, listed as BB_IVAO_vert_offsets_* in the downloads and recommended for the X-IvAp users. LiveTraffic can and shall use them, too. These files make the aircraft roll on their wheels on the ground rather than sitting on their belly. There is some educated guessing as to the vertical offset of models, but still the most accurate way of having them roll on their wheels is the VERT_OFFSET Tag in the BB_IVAO_vert_offsets_* files.
Follow instructions's many files and easy to screw up, but in essence all archives need to be installed into Resources/plugins/LiveTraffic/Resources/CSL.
Essentially, each CSL package is one subdirectory under CSL. Each package directory must contain an xsb_aircraft.txt file, which describes the planes included. (This is the file which shall include VERT_OFFSET lines to make planes roll on their wheels.) The actual object files are often but not always organised in nested subdirectories. The Bluebell installation should then look similar to the following:
Resulting folder structure after Bluebell installation
You can and should verify the correct installation and recognition of installed CSL packages by starting X-Plane and taking a look into Log.txt. There shall be one line per CSL package under plugins/LiveTraffic/Resources/CSL like below, which matches the installation in the screenshot above:
Log.txt (extract)
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/ShippedCSL/XCSL_CARS/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Leipzig_Air_VA/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Mil/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Jets/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Heli/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Airbus/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Repaints/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_GA/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Props/xsb_aircraft.txt
LT: Loading package: /Users/xyz/Applications/X-Plane 11/Resources/plugins/LiveTraffic/Resources/CSL/BB_Boeing/xsb_aircraft.txt

Ground Traffic

LiveTraffic can identify, that tracking data comes from ground vehicles. Some of them carry ADS-B transponders and send the same kind of infos as planes do.
For this purpose, LiveTraffic ships with a CSL model of a FollowMe Car in the Resources/ShippedCSL directory. Author of the FollowMe Car model is the X-CSL team, many thanks for their kind permission! Find the original here along with many other models offered by them.
No action is required from your side.
Advanced users only: If you wish to use a different model for display of ground traffic, then:
  1. 1.
    Install its CSL model somewhere. If it is placed in a new base directory include this directory in Settings > CSL.
  2. 2.
    Put its type code into the Ground vehicle type field of the same settings page.

Additional CSL package paths

LiveTraffic is able to read CSL packages also from other locations. If you have CSL packages somewhere else you can point LiveTraffic to them. This certainly also goes for the above recommendations: If they are on your disk already somewhere then just let LiveTraffic know.
See Settings / CSL for the configuration options.
Other packages will work to a certain extend only. Over time, differences in package formats (especially content of xsb_aircraft.txt and how to provide liveries) developed. LiveTraffic sticks to the original standard.
Other packages (like X-CSL for X-IvAp) provide several liveries in one OBJ8 file. LiveTraffic can process such packages, but only uses one livery. This forum post summarizes it.
The Python script CSL2XSB can try converting those packages. It is known to work with X-CSL.

X-Plane Settings

None of the following settings hinder LiveTraffic to display traffic. But they may affect the user experience:

Draw parked aircraft

...should probably be off. LiveTraffic won't display parked aircraft per se, but sometimes aircraft can be followed up to their parking positions. And it simply looks better if there is no other aircraft then.

AI / Multiplayer Aircraft (for TCAS)

If interested in TCAS: Configure number of other aircraft (documentation: X-Plane 11, X-Plane 10). These additional aircraft will represent those aircraft shown on a TCAS display or on some maps (like X-Plane‘s internal map or Little Navmap and others). LiveTraffic can draw many more aircraft into the sky. But - depending on their implementation - some TCAS displays or maps display at most as many blibs as there are additional multiplayer planes. There is - independent of implementation - a global limit of 19 AI aircraft. The closest planes out of the many in the sky will be mapped to the multiplayer planes and will appear on a TCAS display. (See here for more background info.)
For TCAS display the type of aircraft doesn't matter. In XP11, to reduce startup delay, you may want to set all AI planes to the same aircraft type like B738. Then X-Plane only needs to load one .acf file.
X-Plane 11 configuration of AI aircraft
X-Plane flies these aircraft automatically, if no plugin takes control of AI planes. So if LiveTraffic is off (or just doesn't control AI planes) you might see these AI planes flying around, controlled by X-Plane. That even includes radio chatter. Hearing unexpected radio chatter is a likely sign of X-Plane flying AI planes.
When X-Plane controls AI planes you might encountered an FPS hit as these planes are rendered with as complex objects as your own simulated plane. As long as LiveTraffic controls AI planes there should not be a noticeable FPS hit due to number of configured AI planes as LiveTraffic does not actually draw AI planes but only uses their dataRefs to inform other TCAS implementations, tools, etc. about the traffic.