Sine you are installing on a Mac it might want a fully formed computer name, like //domainname/computername. Your Windows computer should have an account name on it, which is the username you have a password for. Short of that I think you are primed for a visit to the Apple store and see what they say. You are asking a Spanish speaking computer to speak Greek or French here.... more accurately, a Windows computer to speak OSX..... or on OSX computer to speak Windows.