MSYS2 MINGW64_NT System is unknown to cmake

I am using a modified version the following suggestion for a msys2 environment on github:

I get the following message during my cmake command:

System is unknown to cmake, create:
Platform/MINGW64_NT-10.0-20348 to use this system, please post your config file on so it can be added to cmake

What does this message mean ?

See this discussion.