D-Link DNS-320L User Manual page 362

Section 4 - Configuration
Read the app description and click Accept.
Once complete, Google will redirect you to the code. Select
the code inside the box and copy it (Use the Ctl/C buttons to
copy).
Under Step 2. enter the email address you just created (or
previously had) and paste (Use the Ctl/P button to paste)the
key into the key field provided.
Click Apply.
D-Link ShareCenter DNS-320L User Manual 356