You can get Wren:AM Web Application Archive (WAR) in couple of ways:
Download binary release
The easiest way to get the Wren:AM is to download the latest binary release.
You can also run Wren:AM in a Docker container. Official Wren:AM Docker images can be found on Docker Hub.
Build the source code
You can also create your own build from the source code. Manual how to build the source code can be found here.