@IJCT hello! I had this issue too!
What I've understood:
You can't load your game directly from dropbox on your mobile device, correct?
Well you are probably using either:
- The shortened link
- Dropbox mobile app link
Both of these will fail. Fix:
Go to dropbox.com on a full internet browser (not mobile, unless perhaps you know how to turn a mobile browser into a full one [eg show desktop page] then email yourself the link and enter that.
IT should now work.