If you can, try installing on a different machine. That may narrow down the problem.
You'll have to try contacting Aspyr then, and hope that giving out MAS keys isn't the only fix.
I won a CD/DVD game from them once and when I found the key didn't work they sent me another. Since you've had two fail the problem might be more serious, but maybe it's specific to one machine or OS version.
I am not interested in any online-bullcrap where I can play games as long as a company supports an online-platform.
I hear that. But if the only options turn out to be download sketchy software from sketchy sites, or not play, I'd personally go with the MAS version.