Try using hololens2 and UE4, but I followed the instructions provided by unreal engine officail website but failed to get the camera parameters

I tried the instructions of this URL(HoloLens Photo/Video Camera in Unreal - Mixed Reality | Microsoft Docs) but failed to get the camera parameters we wanted (eg.the location,angle,view,scale).We can’t capture any texture and can’t show the feed.We used the blueprint methods(we are new to UE4 and Hololens2), so maybe we tried something wrongly or we missed some important operations but we don’t know.And this is my first question on stackoverflow. I really hope that someone who knows them it well can help me fix it. And if possible tell me a proper route to learn hololens 2 and UE4 developing. Thanks a lot!