Now the Metavido package (previously known as Bibcam) supports URP by default. You don't need to use this package any more.
This repository contains a URP custom renderer feature that adds URP support to Bibcam.
I implemented the feature in a single script file -- BibcamBackgroundPassFeature.cs. Copy it into your project and enable it in the renderer settings. Then the background drawer works as on the default built-in render pipeline.