Hello, there.
I'm sorry you've been having troubles for several days now. If your WiFi connection requires a username as well as as a password, I assume you are are referring to a webpage that you log into, correct? Unfortunately, most school and business networks are not set up with video game consoles in mind. Your game system is probably being blocked by that login page. You will likely need to get some help from the organization’s IT department or network administrators for help bypassing that login page. If the network is compatible with the system, they should be able to help you get it connected.
If you are connecting to a router that you own, you should see if you can disable the login page. If you can do this, your system should be able to connect.
If what you are describing is NOT a login web page, please describe your issue in more detail and the tech forum community may be able to assist you further.