Good evening, I am happy with my dropbox and would like, in addition, to keep an SSD backup. I did purchase an external SSD but I don't find how to synchronise my existing dropbox with this new empti device. Of course, I did copy and paste from my local pc "dropbox" directory, but this does not include the files that are exclusively on dropbox. So please how could I proceed.

A possible alternative, if you're comfortable with using command line, is the unofficial, unsupported dbxcli utility.

Downloading my Dropbox on an external SSD drive