Hello Li,

Although, this is not directly supported feature. To get the jod done, please put following code to your functions.php

add_action('user_register', function ($userID) {
    global $userMeta;
    $roleToAutoActive = 'subscriber';
    $role = $userMeta->getUserRole($userID);
    if ($roleToAutoActive == $role)
        update_user_meta($userID, 'user_meta_user_status', 'active');
}, 20);

Don’t forget to replace $roleToAutoActive = 'subscriber'; with your targeted role which shall activate automatically.

Although, the user will activated but they will see default admin approval required message. To get ride of that, use ‘Do not use AJAX’ checkbox and use custom redirection where you can write something to show some direction to user.

Thanks.