Microsoft Dynamics GP 2016 was released in May 2016. Dynamics GP 2016 R2 was released in December 2016. Here is a quick list of all the resources you need:
Product Release Downloads for Microsoft Dynamics GP 2016
Dynamics GP 2016 System Requirements
Dynamics GP 2016 System Requirement s Web Components
What’s New in Dynamics GP 2016
What’s New in Dynamics GP 2016 R2
Features Since Dynamics GP 2013