I tried:
BACKUP_LOCATION = "C:\\Make Believe Folder"
But WebGISDR says:
Cannot access the location "C:\Make Believe Folder".
And Process Monitor says that the program is trying to access the following path:
C:\Program Files\ArcGIS\Portal\tools\webgisdr\"C:\Make Believe Folder"
I know the C drive is a little contrived. However, my real destination is likely going to be quite similar (e.g. "Z:\") because we use mapped network drives at my company.
I'm using ArcGIS Enterprise 10.7.1 on Windows Server 2019.