If you are off-campus, in order to verify that you are an RSU affiliate, you will be asked to login using a student domain login and password.
This will be the same login you use for your student e-mail. Try using the username portion of your email id: sdfirstnamelastname (such as sdjanesmith). If you have not set up a password, try using your student id as the password. Go to this link to reset your password.