Excellent! I know they have a FAQ or something about it somewhere.
Hmm, that's pretty weird. We uploaded a good deal of keys for the game. I'll check into the system to see what's up! Thanks for letting us know about that.
UPDATE: Well, I can see some keys have been claimed already. Not sure why they don't show up for you though. I will try to contact Itch.io to see what's up!