Using New Outlook on Windows for personal email, calendar, and contact management
That is Outlook New, not classic. All of the suggestions for registry editing, etc depend on Outlook Classic Desktop being installed and functional prior to the installation of Outlook New. Installing Outlook New has no effect on Classic Desktop, both will run at the same time. The registry stuff is to keep Outlook New from taking over and preventing Classic from launching. If Classic is not already installed, they do nothing.