How we can map the existing user with the access_token and authorization?

[fazalerabbi]

I have an application in which I have to integrate the zid store. But I am facing the issue to map the access_token with already existing code. code snippet in this repo and checking for access_token as zid-manager-token it does not exists then create the new user. But I have already a user. I need to map it with that user.