It is working on every Linux distribution out of the box with the limitations of disabled features from the openssl client. It also works on BSD and other Unices out of the box, supposed they have/bin/bash and standard tools like sed and awk installed. MacOS X and Windows (using MSYS2) work too.
On github you will find in the master branche development versions of the software -- with new features and maybe some bugs. For the stable version and a more thorough description of the software please see http://testssl.sh/ .