If you get the message to complete installation of Norton 360 on MacOS by enabling the Norton System Extension and it gives instructions that don't apply to the latest releases of MacOS, go to Settings, Privacy & Security, Developer Tools. Under Developer Tools, toggle the switch off (if already on) and then on (you will need to enter your password). From there, you should be able to activate the Norton System Extension and complete your installation.
If that doesn't work, try removing the extension by selecting it and clicking on the minus (-) sign. Then reinstall or allow the application to add the extension again.
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