Once the download is ready, create a new Unity project and import the package. A new "Umbra"-menu appears to the toolbar through which you can create a new Umbra Runtime component.
Click below to copy a link to a publicly available umbrafied 3D scene.
Paste this to the Umbra Runtime component as a Public Link.
Voilà, you're now streaming large 3D into Unity. You can even build an app using the scene and deploy it to, for example, an Oculus Quest.