add following code in your theme’s (child theme’s if using) functions.php

add_filter( 'fep_get_user_groups', function( $user_groups, $user_id ){
    $groups = fep_get_option('gm_groups', array());
    if( $groups && is_array( $groups) ){
        foreach ( $groups as $group ) {
            $user_groups[ $group['slug'] ] = $group['name'];
        }
    }
    return $user_groups;
}, 10, 2);