If you want to use with LimeSurvey 3.xx, you can t directly, it s broke plugin management. You need to change in file "AuthWPbyDB.php" at line 22 : @version 1.1 at @version 1.1.1 (3.xx compatibility) class AuthWPbyDB extends \ls\pluginmanager\AuthPluginBase at class AuthWPbyDB extends (...)