Hello,
Don't really have a solution for the Briefcase but have, I think an advice and some alternative (there is a lot of them) :
Windows Briefcase is a tool not to mirror but to synchronize two folders. Mirroring drive, depending the content must be a way more complex than simply synchronize two directories. Synchronize is used when you want duplicate only data (no program/software/OS...) and between two machine without a permanent connection. It's often used for bad purpose with poor result (for migrating data from a disk to another by example).
So, maybe a more specific question (why would you copy, what would you copy, will you maintain the two versions sync...) would have a better response and will drive you to a duplication, a backup/restore or a ghosting tool.
Nevertheless, for directories sync, Briefcase is a deprecated tool and a lot of other (even free and Windows) existing to do the same thing. Wikipedia could be a start (a page on Briefcase exist on it...) with a page on directories sync tools :
en.wikipedia.org
rsync/rclone are the tool by default for most of CS/IT specialists. But other tools could be easier to manipulate or have a better GUI for you. Or have way more option that just sync files. Maybe on the list will you find your dream tool.
Hope this help !
