We're aware of an issue with Facebook purchases for all King Games and our team is on it. 🛠️ Hang tight while we fix things! You can still enjoy the game, and we'll keep you posted once it's solved.
There was an update put out recently which tackled the issue of Android devices not connecting to FB properly, check you have it to begin with. If you already have it, what happens if you log into your FB directly from the site and then hit connect in the game?