Half of the help requests I got on Discord are because the installation steps weren’t followed. Please follow them.
Make sure you have a compatible version of Godot Engine (Godot 3.4 → 4.x).
For updating, check Updating The Plugin
If you prefer to follow a video tuto :
Make Your BulletHell or Shooter Indie Game NOW With This Godot 4 Plugin | BulletUpHell Tutorial 1
Download the plugin from : https://bottled-up-studio.itch.io/godot-bullethell-plugin
Unzip it and put the “addons” folder so that it’s at the root of your repository so that your filetree looks like this :
DO NOT open an example scene before completing all the installation steps or it won't work.
Make sure in project settings > extensions
that the plugin is enabled and that in project setting > autoloads
that Spawning.tscn is in the list and enabled. If not, select the Spawning.tscn scene and add it to the autoload list by clicking on the Add button.
RESTART THE EDITOR