Oracle integration to MS Active directory /create roles n assign to AD

I am working on project to integrate our Oracle database to MS active directory.

have done the following steps and I can connect to the database using user "EXTERNAL" and it works great.

Linux side: created AD account, defined Kerberos service name in Linux Kerberos host, created keytab file, updated the server's sqlnet.ora file

Client side: updated the sqlnet.ora file with krb5.conf, etc.

DDL for my user account:

CREATE USER pwkrpaud IDENTIFIED EXTERNALLY AS 'pwkrpaud@u.phxhealth.com';

GRANT DBA TO pwkrpaud;

GRANT CREATE SESSION TO pwkrpaud;

Question: 1. How do I map database schemas and roles to active directory groups and Oracle users?