iCloud calendar not showing in Outlook local app

I am using Outlook 16.95.1 on a Mac. I have an iCloud account which I have added to the Outlook. I see the emails fine, but not the calendar - on the left panel where all the calendars are listed (and can be checked on and off), it doesn’t list the iCloud one at all. This happens on 3 different computers with Outlook. It works fine with my EM Client app, so I know that the iCloud account is successfully sharing its calendar. But Outlook doesn’t see it. Again, the issue isn't that the appointments aren't sync'ing or that I don't see the appointments in the calendar view, it's that the account doesn't appear at all in the left panel with the other accounts.