I can’t find information on how the user account for staff users works, they are not automatically set up as users (members), do they need to open special accounts for member status?
Staff and members are two different entities.
If you want your staff accounts to also have member accounts, then you’d need to set that up for them (e.g. adding them as members in the Ghost admin). They can also do that themselves in the frontend though.
Does this mean that the contributor or author must open another account as a member, in order to, for example, comment or respond to comments under his article?
Two registrations and credentials for such basic use of the site, it doesn’t make sense to me, but ok, that’s how it is.
Is there an option for me as an admin to add staff to memeberse?
Yes, that’s how things are currently implemented.
You can just add a member in the Ghost admin. Click on “Members” in the left navigation and then the “New member” button on the top right.
Yes, I know that, but I need the possibility for the staff to be a member at the same time, with unique login data, and not to take care of duplicate credentials for a single web site.
Perfectly doable.
Email/password as credentials only works for staff accounts anyway.
Members log in works with email magic links - no passwords.