According to the instructions the card should be registered right away - it was not.
Also acc. to the instructions the path for manual registering should be
which also didn’t work for me.
I had to register the card by adding the path
to lovelace’s resources.
Hopefully this will save some time for the next poor soul trying to get this to work!
Side note: don’t forget to add the
vacuum_entity property if you want buttons to show up.