@Jatheish, the main news post for the release of CrossPlay needs to be edited. It incorrectly gives instructions for enabling CrossPlay on a Nitrado PC Server:
However, ONLY Nitrado XBOX Servers are capable of enabling CrossPlay. I purchased a PC server from Nitrado with the expectation of being able to use CrossPlay because of this post. When I couldn't find the option in General > Settings, I submitted a support ticket. This was the reply I received from Nitrado Support: