The Mixed Reality Forums here are no longer being used or maintained.
There are a few other places we would like to direct you to for support, both from Microsoft and from the community.
The first way we want to connect with you is our mixed reality developer program, which you can sign up for at https://aka.ms/IWantMR.
For technical questions, please use Stack Overflow, and tag your questions using either hololens or windows-mixed-reality.
If you want to join in discussions, please do so in the HoloDevelopers Slack, which you can join by going to https://aka.ms/holodevelopers, or in our Microsoft Tech Communities forums at https://techcommunity.microsoft.com/t5/mixed-reality/ct-p/MicrosoftMixedReality.
And always feel free to hit us up on Twitter @MxdRealityDev.
How to find documentation for Unreal 4 Mixed Reality and Hololens 2 Emulator
There have been many updates to the Hololens Emulator and now a Hololens 2 Emulator is available. Basically the Hololens Unreal 4 app runs on the PC and drives via WiFi to the Hololens 2 headset, in the same way as Hololens 1 did, but you can still use the new Hololens 2 emulator
The documentation for Hololens 2 emulator is at Using the HoloLens Emulator
The MixedReality Unreal Samples and contain the sample Hololens 2 App.
The Unreal engine pre-requisite for Hololens 2 covers this from the Unreal 4 entry points. The [Windows Mixed Reality - Unreal development overview](https://docs.microsoft.com/en-us/windows/mixed-reality/unreal-development-overview] cover this from the Windows Mixed Reality that is familiar to Hololens 1 users