CD key and Production Activation code? Two different things on Steam?

[cheese1]

Okay I'm having an issue with a cd key from steam involving my heir to the throne and divine wind. I bought these games for my friends birthday, but he has a mac and the latter two copies are not supported for mac on steam. So I went to a 3rd party and they had an update for Paradox's expansions that would enable him to install the updates to his computer. But the updates require a product activation code. The code we enter in the activation space rejects the CD key. So I sent an email to paradox and the third party. Paradox gave me an automated message basically telling me there's no codes to the game. I'm confused because I thought a CD key is the same thing as an activation code? The CD key activates the product, and I know the purpose, to prevent pirating, and theft. I went on steam to learn more about product activation because thats what Paradox pointed me and I found this link.
https://support.steampowered.com/kb_article.php?ref=5414-TFBN-1352

Can someone help me with this issue? I can understand if this is a bumpy trip due to licenses and different computers etc. But I purchased the game, I have a CD key that activates my product and a receipt. I really don't understand the difficulty, when the issue of a cd key is to prevent theft, and I have a CD key because I purchased the game therefore proving my ethical credibility as an honest customer. Please Help!

 

[Felicity]

CD Keys often don't carry over to different sites; so if you bought it from a different site, it won't work on Steam, and vice versa. Steam codes in particular ONLY work on Steam.

 

[AndrewT]

No Paradox game requires a code to install or play, they only require codes to register the games here on the forums (which are often termed CD Codes by Steam etc, but actually aren't). The Mac version is written and supported by Virtual Programming www.vpltd.com not Paradox, and they supply all needed codes to install and to register here.