Invite plugin confusion

In the invite plugin settings page there are some instructions as such:

Subscribe page for invitation responses
Add subscribers confirming an invitation to this list

My English is not so good so I’m confused as to what those words mean, especially “Add subscribers confirming an invitation to this list”. What does that mean?

Also, I tested it successfully but this is what the user sees after clicking the “Confirm” link in the email:

Thank you for confirming your subscription to our newsletters. The newsletters you are subscribed to are listed below

None of them

But indeed that user is subscribed to a list so why does the plugin say “none of them”?

It’s impossible to follow the instructions for this plugin. . . I had to disable it.