Second sentence of error message states:
It does not contain a top-level __init__py file.
The zip you posted has that file and other relevant files inside a folder named
babelio_notes. The zip also contains Apple artefacts that need to go.
On the first page of a search for
babelio_notes I found this thread ==>>
Mobilererad->Forum Français->Software->Calibre extensions. Try the babelio_notes.zip that's posted in there, its construction conforms to calibre's requirements Ψ³
BR