I have the same issue as this guy at https://github.com/itchio/itch.io/issues/763.

I cannot buy the game via paypal.

Contact support@itch.io if you are still having problems with your purchase.

The staff at Itch handles all the payments/downloads, hopefully they will be able to help.

(I already use the preferred payment method mentioned in the link)

i will contact the support. Still doesn't work.