Does this plugin support permissions per-user? (FAQ)
Yes and no.
The plugin supports global permissions (add, edit, delete) for users who are logged-in.
You can implement the group permissions feature of RainLab.User or your own criteria using one of the (free) 3rd-party plugins that offer a user permissions system for RainLab.User. This would only require you to create your own wiki partial in the CMS section in order to handle these permissions (but you are likely to this anyway to match the design of your site).