So, I just bought the Deep Ocean addon. Store Page says, content will be activated after purchase.
UPlay plage of Anno 2070 says "Owned DLC: Deep Ocean". Cool. Now when I start the game, I get prompted to enter
an activation key.
Well, after searching the Internet for about 30 minutes, I finally found the place where I can find the keys for my purchased games; I simply enterd in manually then and it seems to work.
So... disregard this.