When I've wanted to use Dropbox (or Drive, etc) to sync app data that needs to be in a certain place (game savefiles, mostly), I've had good luck just moving the data directory to my Dropbox and then symlinking from the original location. That should be doable on Android with any old terminal program, though you may need to root the device just to install basic command line tools like "ln".
That's not exactly how dropbox for android works [0].
It doesn't sync a folder on your phone that you can modify, it syncs the metadata and downloads files when you specifically ask for them. Local storage is used as a cache, you can't just add files and expect them to be uploaded without uploading them from within the app.
Comments
When I've wanted to use Dropbox (or Drive, etc) to sync app data that needs to be in a certain place (game savefiles, mostly), I've had good luck just moving the data directory to my Dropbox and then symlinking from the original location. That should be doable on Android with any old terminal program, though you may need to root the device just to install basic command line tools like "ln".
That's not exactly how dropbox for android works [0].
It doesn't sync a folder on your phone that you can modify, it syncs the metadata and downloads files when you specifically ask for them. Local storage is used as a cache, you can't just add files and expect them to be uploaded without uploading them from within the app.
0: https://www.dropbox.com/help/82/en