Limited Access to categories?

There are no real folders in the “visible” part of WP.
As for limiting the access to categories, see the Plugins section of the Codex: https://codex.www.ads-software.com/Plugins
(look for Restriction)

I found the limit categories plugin that Owen Winkler wrote and it’s pretty nice but the problem with that plugin is I can tell it to limit categories by Administrator, Editor, Author and/or Contributor. But there are going to be lots of contributors and I don’t want something this wide in scope. I’d rather have it that ‘poster x’ can only post to the ‘poster x’ category but not the ‘poster y’ category and so on. This is too vague. I saw another one called Page Restriction but what’s the difference between a post and a page? They seem to be the same but they are not.

That plugin does exactly what you asked for: “allow certain users access to only one category”.
With the Role Manager plugin you can have n+1 different roles (besides the one you’ve listed).

None of the known solutions work on an individual user ID# basis.

what’s the difference between a post and a page?
Huge!
https://codex.www.ads-software.com/Pages

OK, it’s starting to make sense to me. I assign a user as an author and that way he can create and edit his own posts but he cannot edit anyone else’s posts. Since we’re using this as kind of a CMS for recording artists I guess we should logon initially as said user, create the posts for him or her and then log off and let them add the content at which time he or she can’t do much else. Right?

Too bad it can’t be done the same way with pages. That does sound really interesting.