TrueNAS Core - NAS looking at wrong User OU

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Running an AD that my predecessor setup to not use the Default User OU name. Instead of Users he called it something else. The AD server has no problem with this, but I cannot get TrueNAS to look at the correct OU. I join it to the domain, but no users are ever imported, thus it will not let anyone access the share.
How do I change the OU to the correct one within TrueNAS?
Should be a place to enter something like:
OU=Users,DC=Domainname,DC=COM
Right? Where is that found?

Where is that found?

Nowhere. We don’t look into a particular OU.

It was my understanding that when joning TrueNas to the AD Domain, that it would pull the users from that and then while those users were authenticated with the domain, they would have access to their own Home folder that other user don’t have access to. But when joining the NAS to the domain, it never adds the users that are already registered within the AD.
I guess I misunderstood what joining the NAS to the domain would do.