MRTK with ZED Mini Passtrouth

Hello, I am trying to get the MRTK to work on my HTC Vive Pro with ZED Mini using Passthrough through the ZED Mini. I use Unity 2021 and the SteamVR plugin. MRTK runs on the Vive with no issues with a black background. However, if I insert ZED_Rig_Stereo into the MRTK Scene under MixedRealityPlayspace and delete the MainCam, I don’t get an error message, but the Pause button is activated and I can’t get any further. Could it be that this is due to SteamVR? Does anyone have an MRTK running with ZED Mini? Thanks