Hey @tsykul, thanks for posting, and building on the Zoom platform! 
The best way to link OAuth to an account id is to save the access_token, refresh_token, and expires date you get from:
(docs: https://marketplace.zoom.us/docs/guides/authorization/oauth/oauth-with-zoom#request-access-token) and JWT decode/parse the access_token to get the account id.
Then save the access_token, refresh_token, and expires date to a database with the accountId as the primary key.
Does that make sense?
Thanks,
Tommy