How to view the To-Do-Bar in Outlook for Mac?
I suppose this is documented by the choice of words:

Outlook for PC - Use and customize the To-Do bar

That view isn't present on Outlook 2016 version 16.13 or less for macOS.

You'll need to run on windows or try the webmail app. If you search "to do bar" in the help for Outlook - you'll find you can't even put things in to the ribbon yet and there's a link to request it on some web site.

In the mean time, you'll likely need to open a couple main windows and look over your tasks and calendar.