Migrate Teams or Sharepoint back to File share

We have a client that just can't understand teams/sharepoint. We've agreed that they should move back to their file share. This is 99% an operations issue and not an IT issue but that's beside the point. They keep blaming the system but it's really their lack of controls, not wanting to learn anything and not being able to take 5 seconds to think about anything. I've kept them from blowing up their entire company like 5 times. For example, they wanted to switch from Gsuite to O365 on a random Wednesday with NO planning. Thought it would take an hour or so. No need to talk to any of the 15 other people who work there who use Gmail all day every day. If I wasn't there, they would have tried to do it. We all know how that would have went.

Anyway, what's the best way to move the data back to their file server in a orderly fashion?

It's less than 1TB of data. They have medium speed internet. I'm testing to see if I can just export it over a weekend but I would rather sync the data out somehow and then just turn it off on a Friday and move back to the server on Monday. Basically just like Bittitan and other software does but in reverse.

Not sure I trust one drive but that could work. It's not that much data so I could mark all the files offline and then copy them to the file server. I would prefer to use some kind of sync software but I don't know any that work with Office 365.

Any help is greatly appreciated.