Question VR - Cardboard - No images

Hi, I am isetting up Unity 2020.3.14f1 and HelloCardboard following the tutorial below for Android/cardboard:
https://developers.google.com/cardboard/develop/unity/quickstart

After the "build and run" I get the images in white in the cardboard, so no images are displayed
In the console I do not get any warning. Only a message stating that the build was completed and successful.

The only warnings I get are the following ones after re importing samples:

Invalid AssetDatabase path: \Assets\Samples\Google Cardboard XR Plugin for Unity\1.7.0\Hello Cardboard. Use path relative to the project folder.
UnityEngine.GUIUtilityrocessEvent (int,intptr,bool&)

Invalid AssetDatabase path: \Assets\Samples\XR Plugin Management\4.0.7\Example XR Management implementation. Use path relative to the project folder.
UnityEngine.GUIUtilityrocessEvent (int,intptr,bool&)

Please, could you help me? Thank you
.

 

I got it moving but very slowly. I still would like to know how to fix the two warnings please.