Outlook Groups is supposedly the core of Microsoft’s Exchange-based collaboration experience, integrated in its Outlook email, calendar, and contacts client. It’s meant to provide shared calendars, shared notes, shared files, and shared messages (handled by Outlook as if they were emails) to members of a group—sort of like SharePoint for humans.
But it’s been available only to Windows Outlook and Outlook Online via a browser since its September 2015 debut. Starting in late April, Microsoft began enabling Outlook Groups for Office 365 accounts’ Outlook clients on MacOS, iOS, and Android (if you have the most recent Outlook versions). Thus, Microsoft finally opened its core collaboration tool to users on all the major OS platforms, unifying Outlook group messages, Outlook group calendars, OneDrive shared files for your group, and OneNote shared notes for your group.
Unfortunately, Outlook Groups is not very useful on any “supported” platform—Windows included—because very little of it works in the native Outlook client. It’s really a browser-based service, not fully implemented in Outlook. As a result, even when you use it within an Outlook app, Outlook Groups keeps opening browser windows (and requiring you to sign in to Office 365) as you try to use the Outlook Group features. It’s a schizophrenic user experience.