How to get DID of Subject who has been issues VC

Question

1. I understand that the Authenticator App / wallet creates DID for user. How can Issuer App access this DID, when issuing VC to that user?

2. I also understood that MS Authenticator App is also the Identify Hub, and stores the issued credential. Is this understanding correct?

3. When we search in indexable attribute in Azure ("Find the credential to revoke"), and get a Credential ID in response, of format: urn:pic:ef720xxxxxxxxxbxxxxed, is this the DID of the issued credential; guess not? Is there any reference of VC on ION / BTC chain? If yes, how the issuer / verifier app access DID of the Credential?

Thank you!