I followed all the instructions to install the api plugin but when I create a post in WP, it doesn't create a thread in Xenforo. All the settings are correct. Also, when I'm logged into Xenforo and I go to a WP post, it asks me to login even though I enabled READ,POST,CONVERSATE. Any ideas?
Did your WordPress account associated with your XenForo account? You can check that by going to http://domain.com/wordpress/wp-admin/profile.php (replace your site address).
So the post is sync now? Regarding the login issue, please take a screenshot of the client edit page in AdminCP.