Yeah, MinGW has been abandoned. It is no longer maintained.
Are you married to MinGW, or do you have other choices? If you have other options, then Cygwin is a good choice for the Windows-on-Linux thing.
Also, if you have the choice, Windows-on-Windows is even better. Just use the Visual Studio project files. You can also use MSBuild, too. For MSBuild, all you need are the VC++ Build Tools, and not the entire Visual Studio. Also see
https://www.cryptopp.com/wiki/Visual_Studio and
https://www.cryptopp.com/wiki/MSBuild_(Command_Line).