Store files in ftp server, accessible only for users from authentication server via OAuth2 protocol and separately for each other

We have in company authentication server with support of OAuth 2 protocol.
We are thinking about ftp repository. Could it be possible to configure ftp repository/server so that we could provide files only for users from authentication server (these users are not in local /etc/passwd list). And each user should see only files assigned to him ? Thank you for any notice, how to solve this or if it is possible.