I just had a really hard time getting one of my Gmail accounts to connect to Outlook 2106. I normally isn’t that hard, but Goggle updates it’s security and made Office 2016 a “less secure app”.
The support and help for both Outlook and Gmail are a little dated it seems. Everything on the web is pointing to:
But it’s now myaccount:
From there, go to your Security setting then “Allow less secure apps”.