If you are on the login screen for the SVG2482AC web interface and see only a single network name, it means your network is not yet split. By default, when you set up the SVG2482AC, the Wi-Fi network names are combined for both 2.4 GHz and 5 GHz bands. To access the 5 GHz network separately, you need to edit the network name for the 5 GHz band to split them.
If you are logging into the interface for the first time, the default username is admin (all lowercase), and the password is password (all lowercase).
If that does not work, try using admin as the username and the default Wi-Fi password as the password.
Once logged in, you can change the 5 GHz Wi-Fi credentials. Please refer to the link below for detailed instructions on how to change Wi-Fi credentials.