Like I said, I've checked Spam every time I've connected my PayPal to itch.io. It's not there either.
I asked PayPal about it. They said there is no problem with my account on their end and told me to ask you (the third party).
About the seller onboarding: I've chosen my Payout mode (Direct), connected my PayPal account to itch.io, and I have a revenue sharing percentage set. Is there anything else I need to do for seller onboarding?