1. Download the Godot editor and export templates from https://godotengine.org/download (standard, not Mono).
2. Download the Material Maker source code and extract it: https://github.com/RodZill4/material-maker/archive/master.zip
3. Start the Godot editor. This opens the Godot project manager. Use Import to select Material Maker's `project.godot` file and edit the project.
4. Install the export templates TPZ file using Editor > Manage Export Templates... > Install From File... at the top of the Godot editor.
5. At the top of the Godot editor, choose Project > Export. Create a preset for macOS (more information). Export it anywhere on your filesystem.
6. Extract the generated ZIP by double-clicking it then run the generated .app bundle.