We have created an integration with Outlook Web Apps. Outlook Web Apps is a version of Outlook provided with the Office 365 subscription. Since it's browser-based, the integration will work on both Mac and Windows. Click here for the complete installation guide.
As an Admin, you can install this on behalf of your entire team.
If you don't have a store button, you're not on the latest version of Outlook for Mac. Follow these steps to get updated:
i. Go to the Help button (in the very top navigation, to the right of “Outlook”)
ii. Choose Check for Updates in the drop-down menu
iii. Update to the latest version of Outlook and come back to these steps when you’re done
The .Net add-in no longer supports scheduling emails from Outlook. You'll need to update to the Office365 add-in to schedule emails.