The most common cause of that is that you're using the HDRP (High-Definition Render Pipeline) whilst SurvivEngine was created using the URP (Universal Render Pipeline). It is simply a material configuration issue, and can be converted over if you so wish. At its simplest, all this entails is just changing the shader each material of SurvivEngine uses (from "URP Lit" to "HDRP Lit" - if memory serves.) You would do this by going to the materials folder and switching each materia's shader property to the desired value. Hope this helps! Let me know how it goes.
