I am trying to create a company calendar, and it shares fine with Windows machines, but when a Mac tries to connect to the calendar and add it to Outlook it's grayed out. I've tried through online on the Sharepoint Calendar page and I've tried emailing the calendar, but it's grayed out in both places.
If you are using a Modern Office 365 Group, verses a SharePoint Calendar you should be able to view that calendar in Outlook online, or the Outlook client (MAC). You'll also get some other great team collaboration tools like a Group OneNote notebook, and a Planner. You'll still have a Team site for your group files. Your post was from a while ago, so you may have found a workable solution, but I thought I would post in case others search for this same issue. What do you get with Office 365 Groups? You'll have an option to opt-in or opt-out members from calendar notifications when you create your group.