Unreal 5.5.4 + Meta XR v78 -> VR Preview does not work with Link

Hi everyone, 

I am new to this forum, and went through the discussions to try to figure out my problem. But to no avail, so here I start a new thread as it seems sligthly different to the problems that others have (or more similar than I thing, but we will see). 

I'm trying to make a basic VR application run in Unreal on the Meta Quest 3. I followed this link to setup everything, and I think that I have everything set up correctly. 

For sure, starting this the VRTemplateMap provided in Unreal, I am able to compile the project as an apk for the Quest 3, copy it on the device, and run it directly from here. 

I'm however running into problem as I also want to be able to run the application on the PC, and display it through the Link (tethered). This is necessary, as I'm working on a heavy application that will require to run on a desktop computer, not directly on the HMD.

However, as soon as I hit the VR Preview button, a static window opens, with a fixed view, and nothing is displayed in the HMD. I've looked around, but cannot seem to find what the problem might be. 

For information, I get the following error message when hitting VR Preview

LogOVRPlugin: Error: [XRCMD][failure] [XR_ERROR_EXTENSION_DEPENDENCY_NOT_ENABLED]: xrCreateInstance(&createInfo, &instance), arvr\projects\integrations\OVRPlugin\Src\Util\CompositorOpenXR.cpp:4563 (arvr\projects\integrations\OVRPlugin\Src\Util/CompositorOpenXR.h:364)
LogOVRPlugin: Error: Plugin failed to initialize. (arvr\projects\integrations\OVRPlugin\Src\Util\CompositorOpenXR.cpp:2829)
LogOvrPlatform: Warning: Could not find 'RiftAppId' key in engine config.  Trying 'OculusAppId'.  Move your oculus app id to 'RiftAppId' to use in your rift app and make this warning go away.
LogOvrPlatform: Error: Missing RiftAppId key in OnlineSubsystemOculus of DefaultEngine.ini
LogOVRPlugin: Error: [XRCMD][failure] [XR_ERROR_EXTENSION_DEPENDENCY_NOT_ENABLED]: xrCreateInstance(&createInfo, &instance), arvr\projects\integrations\OVRPlugin\Src\Util\CompositorOpenXR.cpp:4563 (arvr\projects\integrations\OVRPlugin\Src\Util/CompositorOpenXR.h:364)
LogOVRPlugin: Error: Plugin failed to initialize. (arvr\projects\integrations\OVRPlugin\Src\Util\CompositorOpenXR.cpp:2829)

Also I checked whether it might a problem with connecting through the link, but Meta Quest Link is well parametrized, and running another VR project that I have from the Unity Editor displays appropriately in the HMD through Link. 

I was wondering whether anyone had an idea, as I seem to have tried everything I could encounter (including disactivating nanite, starting from an empty blank project, ...)

Cheers