On the Creator Dashboard there is a Payments tab under which we can see the list of individual payments and email if we need to contact the buyer if there are purchasing issues, but there's a directive not to share it or use it for marketing, so that's why you might not get a thank you email or announcement crediting you.
But I'm sure it's appreciated, e.g. I recently received an email notification from itch.io that someone paid $20 for one of my pay-what-you-want games, and I immediately checked my dashboard to admire that generous donation, which by the way also pushed my earnings over the $20 minimum to get a payout.
I suggest also leaving a nice review in their discussion board and maybe mention you paid more than the minimum to support the developer - that'd be a nice reminder to everyone else that they can do the same.