Steam CKII on OS X works but has steam key glitch

[unmerged(768029)]

On OS X, the game runs and allows saving.

Sometimes, when the game is launched, a big Steam notification appears in the lower right corner and says "You have to enter the following Steam Key" but doesn't tell me where or how to enter it.

This covers up the minimap, and it makes it hard to click the button to start the game, but beyond that it drives me wild with curiosity, wondering where the game will accept the key as input. There doesn't seem to be any menu that would accept it.

Edit:
The notification window claims that Shift+Tab will close the window. This does not work.

 

[Sopot]

The steam overlay opens up via shift+tab, from there you can tell it to stop prompting you about CD keys. Steam overlay is apparently buggy with Mac.

The notification itself is nothing to worry about, it's telling you that to play on the metaserver for multiplayer, you'll need the CD key to register on these forums. You have already done that however.