Reply To: Documents – types and categories
Ooops. Read the manual, eh.
To help others – in case anyone else makes the same mistakes… (they are in the forums but back a bit).
Firstly, I needed to install another module – I used https://wordpress.org/plugins/wp-media-library-categories/ and then the categories appeared.
The I needed to give my documents page documents-finder as a slug.
Now it all works.