As I'm sure you already know, Microsoft doesn't support add-ins on Outlook for Mac in the desktop edition at all.
For starters, be positive that you have enabled Salesforce App for Outlook. You can do this by clicking Setup > Administration Setup > Email Connect > Salesforce App for Outlook Settings. There will be a checkbox next to "Enabled," make sure this is checked. Above this you will find an overview to show you how it all works.
If your company aliases the Office365.com domain (ie:
http://owa.mycompanywebsite.com), then you need to whitelist any domains you use outside of
*.outlook.com in the Microsoft Outlook Web App Whitelist section under the previously enabled section.
If you've already installed the App from the Microsoft Office Store (link), or enabled via the Exchange Admin Center/ECP, then this should be all you need to do to enable it.
After you've ensured these steps have been completed, use Chrome and log in to outlook.office365.com and look for the new
Salesforce add-in by opening any email.
I recommend watching this short video (link) to see a brief overview of setting it up for your entire email organization.
For more information, see the Salesforce documentation (link).
Upon further research, it appears Salesforce doesn't support event syncing to Office 365 other than basic information. For events, it requires a downloadable add-in that is not supported on Mac (see here). I've researched and found a third party plug-in that seems to do exactly what you want, and here is a link to Cirrus Insight. I have no experience using this app but it seems like it might be perfect what you you need.