Magisk Manager requires you to have an unlocked bootloader so your SuperU app is installed in order to work. One of the main advantages of this systemless method is that you can reverse the root at any time and do it automatically. This means you can still use certain apps that don't work on devices with active root permissions.
If you already have a rooted device, from Magisk Manager you can install the Magisk module by downloading and installing it through the recovery menu on your device; so this app is better suited to users with some previous Android knowledge.
Android 4.2 or higher required