For donations most cards will work through PayPal. If it's a prepaid from Walmart it'll probably work just double check what card it is on the bottom right and compare it to the PayPal website.
When you go to donate you have the option to sign in as a guest (no account needed as Jonx said) but be sure you have everything correct in the payment (i.e I did guest account but didn't use my correct email due to error and never got receipt to help validate the transaction through my bank).