You need to print a paper to give to your professor. A classmate says you can print to a USB printer, which is connected to another computer. You try to add to your printer list and get prompted for…

The prompt for a password for a shared printer relates to authentication on the sharing computer, not the local user's administrator group membership on their own machine.

Whether your computer is part of a domain or not doesn't inherently explain being prompted for a password in a workgroup sharing scenario, where Password Protected Sharing is a specific setting.

If your computer was not on the same network as the printer, you would not be able to connect or be prompted for a password; the prompt implies network connectivity exists.

When Password Protected Sharing is enabled on a computer, any attempt to access its shared resources, including printers, from another computer will require the user to provide valid credentials (username and password) for an account on the sharing computer. This is a common security setting in Windows workgroup environments.