I recently ran into a problem trying to install the latest version of Cubase. Below are a few of the errors I encountered:
Error changing permissions in 0755 in /System/Library/Extensions/AuthenticationSupport.plugin
Error changing permissions in 0777 in /System/Library/Extensions/AuthenticationSupport.plugin/Contents.plist
Error changing permissions in 0777 in /System/Library/Extensions/AuthenticationSupportEnabler.plugin
My initial inclination, being a developer, was to use the terminal and sudo chmod the permissions which didn't work. If the previous statement doesn't mean anything to you, chmod is a unix utility that's part of macOS but only accessible by the terminal, that can change the permissions of files (edibility) of files.
This, of course, did not work as I encountered the same problem when attempting to update drivers on my Mac Pro for a nVidia graphics card.
macOS post 10.10, features System Integrity Protection, which prevents various system files from being modified by other software. This is a good idea except when it creates a problem like trying to update Cubase from versions. For me, I was upgrading from Cubase Pro 7.5 to Cubase Pro 9.5, but this could happen with Cubase 8, Cubase 8.5, Cubase 9 and the various versions of Cubase like Cubase Artist and Cubase Elements.
The process is as follows: Disabling the System Integrity Protection, installing the software and re-enabling System Integrity Protection. The steps are outlined in my nVidia post but below are the same instructions.
Verify you have System Integrity Protection enabled. Go to the terminal (the macOS terminal is located in applications/utility) and type the following command into the window. This should return "enabled".
Restart your Mac and hold down the Command-R keys during startup to boot into recovery mode. (alternately, hold the option and select the recovery partition). The recovery partition will take longer to boot than normal.
You should see the macOS installer prompt screen. Ignore it and go to the Utility menu and select the terminal option. Run the following command in the terminal.p> Ignore the installer prompt and select from the Utility, Terminal and run:</p>
Reboot normally. Install the Cubase software, even if the rest of the software installed successfully.
Reboot again into Recovery mode and go to the terminal. Run the following to re-enable System Integrity Protection.
Now you can reboot normally and start using your software!