D-Link DSL-4320L User Manual page 23

Section 3 - Getting Started
To use the mydlink service (mydlink.com or the mydlink Lite app), you
must have an account. Select Yes if you have a mydlink account already,
or No if you want to create one. Click Next to continue.
If you do not want to register at this time, click Skip.
If you clicked Yes, enter your mydlink account name (email address) and
password. Click Next to register your mydlink account with the router.
D-Link DSL-4320L User Manual 19