Thank you for pointing this out! I had to go to the OWA page, add the add on, then go to an OWA session, open the Evernote add-in from a message, login to Evernote and provide my password. Only then was I able to get the Evernote plug-in to appear on my Mac Outlook client!
It looks like Microsoft has finally released an upgrade to Outlook for Mac: http://blogs.office.com/2014/10/31/new-outlook-mac-available-office-365-customers/. There are two items that I need to make this long-delayed upgrade usable: Evernote plug in and GoToMeeting plug in... Is there a timeline for an Evernote plug in for the new Outlook for Mac? Greg