[J29194132705]

using Anthonym16's advice here I was able to get the plugin functioning to register new users. In 3.8.2, returning users couldn't get in, so I changed the lines,

$userid = $vbulletin->db->query_first_slave("
  SELECT userid
  FROM ".TABLE_PREFIX."user 
  WHERE LOWER(email) = LOWER('".mysql_real_escape_string($userData[0]['mail'][0])."')");

and removed the mysql_real_escape_string() function call. It works!