If you’re using Outlook 2016 version 16.0.8431.2079 (released on September 12th) and try to set up a new account using Exchange as an account option, you'll notice that you can't.
That's because with the September 12th update, Microsoft introduced something called "Simplified Account Creation". The purpose of this change was to make it easier for customers using their Office365 service to set up their Office365 accounts in Outlook 2016.
What it also did, however, is make it more difficult for people NOT using Office365 to set up their own email accounts when using Exchange ActiveSync. That said, they did release a registry fix to disable simplified account creation:
Backup and Update Registry to Disable Simple Account Creation in Outlook 2016
See: Instructions Here
Once the steps above are completed, you can add the EAS account without trouble. it is not a hard procedure, but you will be doing so at your own risk.
Alternatively, you might alsoAbe able to bypass Simplified Account Creation, by adding the account via the Start >> Search: Control Panel >> Click: Mail Account (Outlook 2016) Icon >> Add new Mail Account.
