Oh boy. I've been going back and forth with support for ODFB for the past couple of days.
Sadly they can't help as the ******* product is S*HT. Or at least the sync program is.
When you sync a folder to ODFB, the program creates ghost files to your C: drive, equaling the amount of data you are syncing. So, if you sync a folder from your D: drive with 50gb, your C: will gain a folder of AT LEAST 50gb in it.
Microsoft said this is by DESIGN.
Those morons just can't get anything right. Who's got a 1tb ssd as a system drive?