To pay with your Credit/Debit Card you have to select PayPal method.
Paypal allows you to pay with card. You dont need and account or be registered.
1- Go back and select "PayPal" and "Continue"
2- Once you "Confirm your Order" you are redirected to Paypal com make the payment, select "Check Out as a Guest"
3- Now you can introduce your details and complete the order.