At the signup page for Post Affiliate Pro / Post Affiliate Network you can choose PayPal in the section of "Payment Information" (you need to scroll down a bit)
Choose the PayPal option and click on the blue button to enter the PayPal details. When you are done, finish the order by pressing Start now button.
EU customers will have to edit the billing details after logging in with PayPal so they can insert their valid VAT number. So you would have to click Previous button to fill in the VAT ID and change any other details you might be interested in and then continue normally with the order process.
NOTE: We are not able to accept direct PayPal payments, only through payment gateways.