I reached out to Patreon support to inquire about the issues some are experiencing signing up (payment declined). They sent me this link to pass along to you if you are having issues with your payment being declined.
The fastest way to retry a failed or declined payment is to add a new payment method. Follow the steps below to retry your payment: While logged in to your member profile, click the Settings link ...
is only available to registered users. Visit the login page if you have an account. Otherwise visit the registration page to create one.