I am sorry for the inconvenience.
Generally, we discourage our users from using the chrome extension.
For every change in the providers' websites, the extension has to be adapted by hand, which makes the extension quite unstable and error prone. It is no longer actively developed, only core functionality such as up- and download is still maintained.
For this very reason, it never left the beta state.
Maybe our portable app is a solution for you? You can download it at https://www.boxcryptor.com/en/download/?platform=portable
If you're using a Chromebook, give our mobile app (supported on many Chromebook versions) a try: https://www.boxcryptor.com/en/download/?platform=android
Else, please contact our support at firstname.lastname@example.org