How to purchase plat through web store with facebook login?

[Cashews]

Im trying to purchase plat through the Web Store with my Amazon account but I cant figure out what to put in the text boxes where it asks for account info because I use Facebook to log in.

[Schnitzel]

I dunno about that, but here's a alternative

https://store.spacetimestudios.com/WebStore/store.jsp?game=069db975-33a5-43be-9d20-a680fbc6537c&x=195&y=147

this is from STS's website