"You do not have access to this folder". Me too. This problem was identified by many people one year ago, and still no response? Does Boxcryptor even look at their own forums?
On the wider stage there doesn't seem to be much progress in resolving the debilitating issues surrounding Chrome OS (Chromebooks, Chromeboxes, etc.), starting with, "Warning!
Native Client doesn't seem to work correctly in your browser. Some features of Boxcryptor had to be deactivated."
I'm guessing I'm not alone in looking for alternatives to Boxcryptor, which is a pity because it served me well for a long time in Windows environments.