SMB Permissions aren't preserved when accessed as external storage for Active Directory User's

I have integrated my existing windows file server and AD with nextcloud. I was using existing Windows File server for folder sharing method as file service for all AD users with different permissions.
I have added the existing Windows File Servers’s shared folders as external storage to nextcloud.

After adding the same folders/shares as external storage through SMB/CIFS how can I enforce same Windows permission when accessed using same AD user login.

The Idea was to have Open Source file sharing app/tool alternative to existing windows file/folder sharing. All AD users are given access with certain permissions to shared folders. How do I enforce the same access restrictions/permissions for the same share/folder when accessed through Nextcloud as an Active Directory User.

I have the same issue. I would like to mount an external storage to Nextcloud, have user’s log in with their AD credentials into Nextcloud, and then have the AD credentials determine what access they have to the external storage.

Currently ldap/AD authenticates the users to Nextcloud, but everyone gets the same access to the shared files. Access is determined by the user account applied when connecting the external storage to Nextcloud.