The biggest problem it that the "network" was set up as a default 'workgroup' on all the Win10 machines. They sign in with MS accounts and have a few shares set up on a workstation for general office files. They have to set the shares up with "everyone" and read/write for the permissions but have so much trouble accessing things. You can't use their MS account to give permissions because the workstations are not aware of the AzureAD account.
They have tried OneDrive and had a ton of issues with files being deleted or moved. I think using OneDrive as a "server" violates the TOS too. The entire setup is so convoluted. They don't even know how they set it up. When they did use OneDrive, they still shared the OneDrive folders on the LAN and browsed them locally.