In case you missed it the Office 2016 ADMX templates are no longer part of the Office Resource Kit like previous version.

You can download the ADMX files here https://www.microsoft.com/en-us/download/details.aspx?id=49030

Also, if you have a bunch of Office 2013 GPO setting you want to copy across to Office 2016 policy you can also there is a PowerShell script on GitHub that will convert any of the configured settings from 2013 to 2016. Very handy if you don't like having to re-creation all you Office GPO setting by hand. See https://github.com/OfficeDev/Office-IT-Pro-Deployment-Scripts/tree/master/Office-ProPlus-Preparation/Copy-OfficeGPOSettings