Setting up sync folder with external hard drive

Hello,

I am trying to set up the default location for the Sync folder to be on my external hard drive (E: drive)
However, once I do this, it does not let me “Add to sync” folders that are on that E: drive.

I want to sync my external hard drive while with out saving data locally on my PC C:drive.

Is there a way to do this?

-Mel