I am getting this error when trying to install it
Library\PackageCache\com.hauntedpsx.render-pipelines.psx@a28da49f24\Runtime\RenderPipeline\PSXCamera.cs(152,23): error CS1501: No overload for method 'SetReferenceSize' takes 3 arguments
Check the Unity version you're using - don't think it works for the newest versions (2022, 2023).
The Github project for the pipeline says "Built for, and verified in Unity version 2019.3, 2019.4 LTS, 2020.1, and 2020.2."