Hm, that is a bit tricky. If you don't have bootcamp with windows, maybe you can borrow someone else's Windows computer and just log in on your Steam account to see the code?
If that won't work either, please contact our support: http://paradox.zendesk.com/home and we'll try to get it solved there.
If that won't work either, please contact our support: http://paradox.zendesk.com/home and we'll try to get it solved there.