Hello alwei.
has two main view modes. One basically shows plain old 2D-Windows in a 3D environment (containing UE4Game UWP App now). Then there is another mode were you have complete control over rendering of stereoscopic images. Have a look at the App views here:
https://developer.microsoft.com/en-us/windows/holographic/app_model
So you need to setup a correct stereoscopic rendering in UE4 first. You need to switch to Holographic view to have 3D stereo access. Then you have to connect this stereoscopic renderings to the devices dx-backbuffers. Finally move the stereoscopic camera by devices sensors data.
I can help you with that, but sometimes UWP can be frustrating. Except stereo rendering in UE4, I have already done all this on a and would love to see UE4 run on it.