StarUML version: 4.0.0

Many solutions have been tried before because of this. Finally, it is found that the official manual states:

To install an extension manually:
1.Get an extension as a .zip file.
2.Extract the file on the extensions path.
	/Users/<user>/Library/Application 	Support/StarUML/extensions/user for Mac OS.
	C:\Users\<user>\AppData\Roaming\StarUML\extensions\user for Windows.
	~/.config/StarUML/extensions/user for Linux.
3.Check a folder in the extensions path and :file:main.js file in the folder.
4.Restart StarUML.

For example:

there is a link to the extension on the official website. GitHub downloads the release version, copies it, decompresses it and restarts it. The official manual will always drop God