the installer ( XML ) create new field unter vbulletin settings, called SOAP API
you can setup then the Key for the soap connection
more is not needed to have this addon work
maybe you should check if the forumpath under includes/config.php is set
for access joomla from vbulletin side, you must install "vbulletin application connector" which you can find here in forum
in the testfiles you must edit the URL to your soap api and the key
you can not access my forum with this examples ( IP is not allowed

)