Boxcryptor Classic for Mac OS X only supports OS X 10.7 - 10.10 and does not support the newly released OS X 10.11 El Capitan. However, we have released an updated version of Boxcryptor Classic for Mac OS X which allows basic read-only access on OS X 10.11 El Capitan so that encrypted files can be accessed also on Apple's new operating system version. You can download it here:
If you already upgraded to El Capitan, you can use this version to decrypt your files and make the switch to Boxcryptor 2.x. You can either use the free version of Boxcryptor or upgrade to an Unlimited account. Existing Boxcryptor Classic customers benefit from a 50% discount on their first year by entering their Boxcryptor Classic serial number at https://www.boxcryptor.com/app/upgrade
IMPORTANT: This does not affect the regular Boxcryptor version which supports OS X 10.11 El Capitan. This only applies to Boxcryptor Classic.