Hello,
Thank you for contacting the support, and sorry for any inconvenience that might have been caused due to that.
The payment has not been completed:

Please ensure that your payment method supports the following:
Payments in USD $
Supports subscription-based payments
You are not using a prepaid card
International payments are turned on
A credit card is needed to be verified with a PayPal account for automatic subscriptions in case there is no balance in your PayPal account. That is a requirement set forth by PayPal, not us
If everything from the above is enabled and working, you can also try using a credit card instead.
You can also call your bank and ask what’s stopping the payment to go through and request them to approve it on your end.
Looking forward to helping you.
P.S. Please send a screencast as well if the issue persists. You can use a tool like Loom.
I completed the payment process again today. It says that I will be redirected to the merchant page again. Unfortunately that does not happen.
How should I proceed further here?
Hello,
Thank you for your patience. Your account has now been upgraded to Rank Math business. You can refer to the following guide for how to get started with Rank Math PRO: https://rankmath.com/kb/how-to-upgrade-to-rank-math-pro/
Hope that helps. Please let us know if you have questions.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.