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.
Zach Sylvester
System/Network Administrator
SmarterTools Inc.
(877) 357-6278
www.smartertools.com