Syncing contacts between Outlook for Mac (2015) and Google Contacts
Can’t sync Outlook for Mac with calendars and contacts in Outlook.com, iCloud, Gmail accounts

Outlook for Mac does not currently support CalDAV or CardDAV. This means that it is not possible to synchronize your Outlook on the web, iCloud, Gmail calendar or contacts with Outlook 2016 for Mac. However, Outlook 2016 for Mac does support iCloud Mail. For more information, see Microsoft Outlook 2016 for Mac compatibility with Apple iCloud.

For more known issues in Outlook 2016, pls check here:
https://support.office.com/en-us/article/Known-issues-in-Outlook-2016--for-Mac-af547e5c-4310-4d41-9944-08b1e842ebe4?ui=en-US&amp;rs=en-US&amp;ad=US