Dear Divyanshu, there have been complaints of issues with the final registration particularly after making the payment. While AIIMS hasnt officially announced any resolution for this, few students who faves the same issue cleared the cache, browsing history, restarted their device and relogged in. It didnt work immediately but eventually worked for many of them. Check if the payment hss been debited from your account. It yes, the process will be completed. It will take time but you will be able to complete the registration process.