It seems you need the original game CDs to get the music on OpenRA. Incidentally, I have both the original 3 1/2" disk and the remastered CDs from the early 2000s -- but no computers with CDs or floppy drives. I'm willing to even purchase the music a third time, but seems OpenRA wants a CD -- has anyone gotten around this?
Does it play the music via Redbook audio? I wonder if you could "burn" mp3s to a virtual audio CD and then mount it.
I just installed openRA and it says you can use an installation or cd. Maybe you could find an installation online and use your unlock key?