The issue could be an issue with either the supporter's account or the creators account.
One common reason for this kind of problem is that the email address hasn't been verified with with PayPal or there is another issue with the PayPal account. If the you haven't yet received any support, this could be the case.
Try logging into PayPal (desktop website is recommended) and check the email has been verified and that there's no other restriction messages.
If there is nothing obvious in PayPal, please try:
- Checking the PayPal account email in Ko-fi's Payment Settings exactly matches the PayPal account email.
- In some cases, forcing a refresh of the PayPal email in Ko-fi's Payment settings (by temporarily changing the email address, saving, then reinstating the PayPal email address and re-saving). In some cases this has cleared a cached value that we use to communicate with PayPal.