Please try adding the given code in your wp-content/plugins/wplms-customizer/wplms-customizer.php file :
$filters = array(
'wplms_course_non_loggedin_user',
'wplms_start_course_button',
'wplms_continue_course_button',
'wplms_evaluation_course_button',
'wplms_default_course_button',
'wplms_expired_course_button',
'wplms_private_course_button',
'wplms_take_course_button'
);
foreach($filters as $filter){
add_filter($filter,'add_membership_support');
}
function add_membership_support($x){
return apply_filters('the_content',$x);
}
Please note the following points :
1. Your vibe course module plugin version must be 1.9.8.4 or more .
2. Make the courses free if you want to use the membership for the course .
3. Assign membership from the backend .