Office 2016 for the Mac – as you may or may not know by the time you read this – is currently available, via an Office365 subscription. See https://products.office.com/en-us/mac/microsoft-office-for-mac?pid=m
With Office 2011 for Mac, your Outlook files were stored within your Documents folder, in the folder “Office 2011 Identities” inside of the “Microsoft User Data” (~/Documents/Microsoft User Data/Office 2011 Identities).
This has changed as of Office 2016. Local storage for Outlook 2016 is to be found within the (user’s) Library folder, in the “Group Containers” folder:
~/Username/Library/Group Containers/XXXXXXXXXX.Office/Outlook/Outlook\ 15\ Profiles/Main\ Profile/Data
(where “XXXXXXXXX” is a 10-digit alpha-numeric string).