The Kirby docs say at Add authors to your pages: Creating authors:
A Kirby user can have different roles
I think, that every Kirby user can have only ONE role at the same moment/simultaneously.
Lets say the Kirby user “John Doe” has the role of an “editor”, then he can not get additional the role of an “author”?!
I therefore consider the sentence quoted to be at least not sufficiently clear and suggest that it should be worded more clearly, e.g. something like:
Different roles can be assigned to a Kirby user, but only one role can be assigned to each Kirby user at any one time. The current role can be changed at every time by an admin using the Panel.