The plugin worked just fine for me.... Until now.
Now I only get the error message, that the shared folder is not readable.
I tried creating new folders in Dropbox, moving the folders to other subfolde, changing the link form https:// to http:// etc. but still couldn't fix the problem.
I even tried downgrading the plugin to 1.2 once but couldn't get rid of the error message.
You seem to have the same problems with your demos on your side!
http://www.hynotech.com/wp-plugins/dropbox-folder-share/
Would be nice if you can fix it asap!
Loved the plugin before and wasn't able to find one quite good as yours!