Hi! Sounds like a problem on itch.io end. You probably bought it for a lower price, so now there's a mismatch. I'll change it back from "name your own price" as it seems to be causing the problem and let the developers know about this. Sorry for the inconvenience!
Oh no, that's unintentional. I changed the payment option to "name your own price" and seems lile it messed it up. I don't know if it's supposed to work this way, but I'll let the developers know. In the meantime I'll switch it back to "payment" instead of "name your own price"