MyBBXP ERROR when posting

MyBBXP ERROR:
(MyBBXPCrossPoster.php:67) You need to enter your cross-post into the "MyBB Cross-Postalicious Post"-Box, please do so and update your post.

I’m confused. Doesn’t this plugin take your post and repost it? Why do I need to enter the whole post again in the box? The box automatically displays this:

This is the discussion thread for !BEGINLINK!!TITLE!!ENDLINK!.

Is there something else I should enter in there?

https://wordpress.org/plugins/mybb-cross-postalicious/