Hi

Once the fees is submitted you cannot change or edit anything in the form. If you wrote your passing year as 2020 instead of 2021 that makes a gap for which you are supposed to submit a gap affidavit/certificate. You could have done a new registration by paying fees again before the last date of the registration. As for now contact the DU officials by email and do as they suggest. If it's a minor error you can clarify it during the counselling.