Hi, You need to IMPORT not ADD the contents of your created project into the original base project. In all project is a Content folder so even if you download a full project, you need to inport all the Assets and not the project. When you have all the project assests loaded go into the maps then double click the Level you want to open.
You are still VR Template project so you start VR as before and its displayed because the underlying project is VR and the assets are imported
see
How To Import .uasset Files Into Unreal Engine 4/5 (Tutorial) - YouTube
see documentation
Textures in Unreal Engine | Unreal Engine 5.2 Documentation