The shader supports URP and HDRP pipelines, in addition to Built-In from Unity 2021. The latest version is by default initially configured to work with all three. If you are getting errors or the materials in the sample scene appear magenta, then you may need to configure your setup:
For Built-In or HDRP pipeline, you may need to configure the shader's Active Targets. To do this, open OmniShade PBR.shader in Shader Graph.Under Graph Settings, press the ➕ to add Built-In or HDRP. For the settings, copy the same from URP (set Custom Editor GUI to OmniShadePBRGUI, Alpha Clipping is On), and save the graph. Repeat the same for the OmniShade PBR Transparent.shader.
For improved shader build times and performance, remove the Active Targets that you do not need (ie., remove HDRP if you only use URP, and vice versa).
Start by opening the sample scene in OmniShade PBR/Sample Scene URP/Sample Scene.unity.
Feel free to move the camera around and browse the sample materials in the scene, and experiment with the shader's parameters to get an idea of what the shader can do.