custum page private course didn' work

I'm trying to folow this tutorial to customize my private course button but not successful... https://wplms.io/support/knowledge-base/connect-private-course-button-to-a-custom-page/ It's my class

<!--?php if(!class_exists('WPLMS_Customizer_Plugin_Class')){ 
class WPLMS_Customizer_Plugin_Class{ public function __construct(){
   add_filter('wplms_private_course_button',array($this,'wplms_private_course_button'),1,1); 

} // END public function __construct 

   function wplms_private_course_button($link){ 
       return '/pacotes'; 
   } 
}
} ?-->

  What i me doing wrong? see attachment if messy code. thanks in advance!