I received the debug log. From the log I think this is what you are seeing.
- You choose Connect to Dropbox
- CC asks you to log in. This appears to succeed.
- CC shows you a "help" dialog saying that you need to choose the library folder. You say OK
- CC show you a dialog with a spinning progress indicator. You never see any folder list.
- After around 2 minutes it stops. I suspect you tapped Cancel.
This is a very strange sequence. There are no network errors and no Dropbox errors, but CC seems to find no folders.
One possibility I see is that there are no folders in the Dropbox account using the credentials (email and password) you logged in with. I never expected that to happen and CC doesn't log it, but following the code I think I would see this behavior. This leads to the question: if you log into Dropbox via the web interface using exactly the credentials you used with CC, do you see any folders? Do you see your library?