2012R2 is EOL.

Dont do it.

The install should work on 2012 R2. I believe 2012 R1 vs R2 is where things actually don't work. But it's still unsupported, so I'd still heavily recommend a server upgrade at some point. Not sure how long dotnet plans on supporting it, we'll be sticking to latest versions of dotnet.

Matt is correct here. If you try to install it on Windows Server 2012 Standard it will fail to complete. But if you install it on R2 it will work I would just use the most updated version you can. But I don't recommend setting up a new environment on an EOL OS. You should try to get on something newer as the longer you sit on that the more liability that will carry.