This usually happens due to an issue related to you PayPal account or your credit card provider. If you are using a credit card with no PayPal account, please try a different card or verify the available funds on your card.
Kindly update your PayPal account information - either link your credit card or update your current credit card information. If you wish to make the payments via direct bank deposits, you need to have your bank account linked to your PayPal account.
Once updated, you can complete your purchase by checking out your chosen creation and choosing the lay-buy option.