Repair Assistant plugin doesn't load with version 4

I downloaded and double-clicked this plugin (in the absence of any instruction) , It opens an instance of MuseScore but then states: "Cannot read file [...]\Repair Assistant.qml - Unknown filetype."

If this plugin is not compatible with this version, the manual needs updating https://musescore.org/en/node/335842 and https://musescore.org/en/node/54721

If it should work, then guidance gratefully received!