Hello, I’m Nathan, and I’ll be assisting you today. My livelihood depends on your positive feedback, so your satisfaction is my highest priority.
Sorry to hear you’re having trouble.
Are you sure you're actually on the wifi setup step?
There is no username for your home wifi network, it would never ask for one.
For wifi connection you'll have to select your xfinity wifi network name from the list of options it scans for and picks up a signal from, then enter your wifi password.
This is not the same as your xfinity account information, email account etc.
It is also different than the registration process, which links your kindle to your amazon account and password.
If you can let me know more about exactly where you're getting stuck, I'll advise further.