Offline Files

I’m trying to setup offline files for a particular user. Under her user account she is a member of Domain Users. When I try to configure offline files, it goes thru the motions normally, but nothing happens. I made her a member of Domain Admins and it works fine. My understanding is that it should work with her being a member of the Domain Users. Is there another group she needs to be a member of. She can’t be a Domain Admin.