Sometimes dumping does not go to well because of some protection. Here a video on some common metadata protections and how to fix it so that you obtain a proper dump.cs, but note that this does not work for "Every" protected unity game. In this video we use Legend Slime as example which has metadata protected.
Requirement:
Computer
Il2CppDumperGUI: https://github.com/AndnixSH/Il2CppDumper-GUI
Emulator: Bluestacks, Nox, VLPlayer...etc
Game engine: Unity