Hard quotas not being enforced

Hello Win IT Pro!
I've got a bit of an issue here. I'll try to explain my team's objective and what we've done.
We're an R&D IT hosting organization. We want to set up network shares for our various projects to buy from us. But we need to limit the size of that network share.

It was decided to setup multiple DFS servers (Server 2016) so we have redundancy if one fails. Next we created a series of folders, and using FSRM to set quotas. Then we give permission (via a Security Group) to that project's folder to the project admin; the project admin will have Full Control so they can create subfolders & manage permissions to their individual project share.

The problem I've run into, that I can't seem to figure out, is that setting a quota on the project folder prevents that folder from exceeding the quota. However, if you make a folder within it (what I'm calling a "subfolder"), and then you'll be able to place files in excess of the quota.

So to maybe illustrate it:
Project Folder: 100GB quota
  > File 1: 90GB in size (does not exceed quota)
       >Subfolder>File 2: 110GB in size (exceeds quota of "Project Folder")

I also tried setting up SMB shares, but the quotas are only sticking for as long as the user's current session lasts. That is, they can map the drive but upon rebooting their computer they can then exceed the quota limit (all are Windows 10). Also, upon restart, the user no longer sees the limit in Explorer "This PC" screen.

I accept that maybe I'm going about this the wrong way. But I thought quotas would be the way to go & I can't seem to find anything on Google searches that helps me understand why this happening. When I read the Microsoft documentation it seems to indicate that a Hard Quota should prevent anything from exceeding this quota (100GB in this example).

So what am I missing? Or is there a better way to go about this?

Thanks a ton for your replies! Happy to provide additional info!