I'm not sure exactly where I found this (I've tried so many things), but I did it and now freefilesync is working. Actually it is to get Dropbox working on a thumb drive, but worked for freefilesync. Just in case someone else has the problem and wants to try this:
Dropbox on a Thumb Drive
1. You can have your Dropbox folder on removable media (a flash/thumb drive) on Windows. If you have a flash/thumb drive, you will first need to mount it. This is done by:
a. Control panel --> Administrative Tools --> Computer Management --> Storage --> Disk Management
b. Right click on the flash/thumb drive, select Change Drive Letter and Paths…
c. Select add, then select Mount in the following empty NTFS folder, browse to your C:, select New Folder…
d. Name the folder "DB Mount", click OK, click OK, click OK. Close Computer Management.
e. You can now access your flash/thumb drive through its removable storage location (drive letter) or through the mounted location (C: DB Mount). Dropbox requires a local drive (the mounted volume).
2 Download Dropbox at:
https://www.dropbox.com/install (You will have to signup for an account if you don't already have one).
3. If you have a flash/thumb drive, install Dropbox to the mounted drive in C:, named DB Mount. Select the this as the location for your Dropbox directory. [actually I just moved my Dropbox folder to DB Mount and it's working.