Instant aadhar kyc? Aadhar Biometric and prefilled form, right? Even though you're asked to submit physical copy of aadhar and PAN, right?
It's bug, same problem exists for several customers.
If you're using Rewardz app and web to sign-up, then still you can't access immediately after opening an account. It will take few days. You will be able to sign-up, when core banking team share your details to Rewardz depart, most likely you will be able to sign-up within a week (business).
It will time longer then expected, it can take upto 45 days, after that you are eligible to raise complaint, so just chill and wait patiently, it will get credited later at once with the backdate, no need to do anything, don't lodge compliant.