I found it. It was user error. 🤦🏼♀️ I did connect the Patreon but I have no clue how to claim keys with it connected. This is not my tech savvy home. Clearly!
It should be the case that if you've connected your Patreon account to your Itch.io account, it just offers you a key for this on the store page for Shimmersnow, right?
I'm actually not too sure how it works from the patron side of things.