Download and install precompiled Plugin
If you wish to not build the plugin from source, you can download the precompiled plugin from the releases page for the right version of Unreal you are using. It does not come with a environment so you will need to create your own Unreal project. Follow this step-by-step guide.
The releases page also comes with additional downloads and links to the several API implementations for ROS(2) and the Python and Matlab API clients for that specific version of the Cosys-AirSim plugin.