Hi nishitparikh27,
ZView isn’t designed to show standard Unity3D UI elements, so you would likely have to modify how the scene is drawn to the ZView display, or otherwise represent the UI with mesh renderers.
I have some concerns about your intention to set your UI as the “background”. UI in zSpace apps typically rest at zero parallax, or in other words the viewport/display plane. This way the UI will be naturally locked in place relative to the display and not move or become obscured by users looking at the scene from a different perspective.
If by background you mean a visual feature that is infinitely far away, like a skybox, then I would recommend taking a look at our documentation titled Mixed Reality Essentials. Here you can become familiar with the terms Coupled and Decoupled Zones. I would strongly recommend abiding by these zones to ensure that users have a comfortable visual experience in zSpace stereo. Skyboxes and other infinitely distant objects with distinctive visual detail should be avoided as much as possible.
Regards,
Alex S.