Administrator Password prevents outsiders from accessing the modems firmware settings. After creating a username and password, you will need to enter them every time you access the modem's firmware GUI located at http://192.168.0.1.
If you are unable to access your modem's GUI using the admin username/password, you can reset your modem
to factory defaults. After resetting your modem, trying accessing the modem GUI using the admin username/password printed on the sticker on your modem.