I am new to working with Wix, so I might be missing something here. I've created a members-only site and added the Wix Forum app and then set the permissions page to "members only." However, when I go to the live site to test adding a post to the forum, there is no option to add a post in the members only site.
Editing View
Live View as logged in member
You need to go to the forum web address. From the member are you cannot create a post.