Question about delegating control of an OU to a specific user

I'm running windows server 2012 R2 in VMware connected to a domain client running Windows 7 in VMware

I created an OU called "catgroup" and I delegated control of catgroup to the user cat.

So when the user "cat" logs on to the client VM how can they access control over this OU?

Is there a program in windows 7 that can open AD users & computers on the server or is a remote login to the server necessary?

If the latter is true, does "cat" have to be in the administrators group to open AD users and computers ? (which seems to be the case from my attempts) 

Windows 7 can not remotely manage Server 2012. You would need the client to be running Windows 8.1 or higher. Then you could use RSAT (Remote Server Administration Toolkit).

It turns out you were incorrect about this. I installed and successfully used RSAT on windows 7.

https://www.itsupportguides.com/knowledge-base/windows-7/windows-7-how-to-install-the-active-directory-users-and-computers-tools/

Windows 7 can not remotely manage Server 2012. You would need the client to be running Windows 8.1 or higher. Then you could use RSAT (Remote Server Administration Toolkit).