If you don't want to register for Paypal or even have a Paypal account, you can still make a payment using a Credit Card.
On your invoice you can click on "Paypal Subscribe" (automatically pays each month for you) or Paypal Checkout (manual payments each month).
On the next page, at the bottom is a button that says "Pay with Debit or Credit Card".
On the next page, you fill out your information and your card details. Then at the bottom is a selection to create or not create a paypal account. You can simply choose to "NOT" create a paypal account. Then just click Pay Now.