My website is set to "Invitation Only", meaning public users can’t sign up directly. Now, I want the signup page to appear only after a successful payment.

How It Should Work:

1. A public user chooses a subscription plan and proceeds to payment.
2. Once the payment is done, they should be redirected to the signup page automatically.
3. The signup page should not be publicly accessible—it only appears after payment.
4. After payment, a one-time secure signup link should be generated, so users can’t share or access it again later.
5. Once they sign up, their subscription status is confirmed.