Plugin to Choose which post categories a subscriber can view or not

Take a look at https://www.ads-software.com/plugins/restrict-user-access/ and https://www.ads-software.com/plugins/content-control/

@sterndata :
I have already tested all this plugin but they are all based on a rights system managed with roles (which is good in itself but not my current need). In my case I need to be able to define for each user (and not their role, which is too generic) the categories to which he has access

As that seems crazy to me ?? and probably not a viable solution when you have a lot of users, it’s likely there are no plugins that do that on a per-user basis. So, let’s back up and talk about what you’re really trying to accomplish.