“Sorry, to quick to judge. You were right:
“Your office365 admin can allocate whatever he wants/needs to a teamsite, albeit within the limits of your total storage pool.”
I don't see why you would implement ODfB in such a manner. We consider ODfB for personal work stuff. And the sharing capabilities are for occasional informal sharing. For regular, lasting collaboration: we create teamsites with document libraries. And ODfB CLIENT is perfectly capable of syncing teamsite libraries. (At least the old version of the client and the future version of the new one).
So in you're case: I would host the files of your 50 folders in 50 libraries en give certain groups read/edit rights in the respective teamsites.”