Hi there,
I have Yosemite and outlook for mac from office 365 home edition subscription.
I have tried to set the US local options and this still does not allow my to active Outlook. Strange thing was I could activate it initially but then it could reactivate and now after several tries of uninstalling and creating new users to reactivate it still wont activate.
Not sure if this help but also sometimes get Unknown Error - Error 0 when trying to activate.
Thank you