You can set this up easily using category permissions. Here’s how:
1. Create a group (if you don’t already have one):
- Go to your Admin → Groups
- Click “New Group”, give it a name, and add the users who should have access.
2. Create or edit the category:
- Go to Categories
- Either create a new category or edit an existing one.
3. Set the permissions:
- In the category settings, scroll to the Security section.
- Remove the default everyone (and any other groups you don’t want).
- Add your specific group.
- Assign the permission level you want:
- See → allow them to view the category
- Reply → allow replies
- Create → allow new topics
4. Save your changes.
That’s it — now only the users in that group can see or interact with the category. Other users won’t even see it listed.