Payments for G2F design are made at PayPal, but you do not need to own a PayPal account to pay: you may enter your credit card's data directly at PayPal and complete your payment. You don't need to register a PayPal account neither.
Once you get redirected to PayPal, just do as follows:
1. Click on "Check out as a Guest"
2. Enter your credit card's data
Address, email & phone number may also be requested depending on your country.