I'm really really disappointed with Dropbox over the last several years. I had an enormous issue as did others with preview of images and photos on my laptop which after a multi-year discussion on this forum with dropbox led me to give up and put them on OneDrive (which is much better at preview of thumbnails) so I could continue my family history writing. But I continued to use Dropbox as my backup solution and as needed for sharing.
I'm again totally disappointed with the effort to backup my dropbox cloud to an external harddrive. I've read all the posts here and on Reddit about the best way to do this. You have to synch the files to your harddrive on the laptop and then copy them to the harddrive (making it a multi-step process). I think I would live with that if Dropbox worked consistently with making files offline. But I can select a folder and say make the files offline (ie on my laptop). Then when I try to copy those to the harddrive I often get errors. Only some of the files in the folders show up offline. Sometimes I have to repeat the procedure multiple times on a single folder to get the files offline.
It is ridiculous that I can't select a dropbox folder and copy it to a hardrive and have dropbox dowload the files either directly to the external hardrive or to my laptop. I consider myself a fairly expert user of Dropbox (10+ years) and used to love it. Now I just tolerate it.
PS I tried cloudmount but ran into some issues with that solution too.