As of 26 February, you will log in with your new Radboud account (firstname.lastname [at] ru.nl) and no longer with your u-/s-/e- or z-account. If you have a Radboud University laptop, you will need to log in less often because you have already logged in at your workplace and authenticated yourself. Just make sure you always connect to EduVPN off-campus so you can access BASS.
Signing up with just your username and password is too vulnerable these days. This is why access to more and more Radboud University applications will be more secured by using the Multi-Factor Authentication (MFA). MFA uses an additional means of identification to establish with greater certainty that you are indeed the person signing up, using your Radboud account. This means that in addition to your username and password, you have to log in with a code received via text message or via the authenticator app.
Without MFA authentication, you can no longer enter BASS
Don't you have MFA set up yet? You can set up MFA via the Office portal. You can choose to log in via an authenticator app or SMS. It's possible on your Radboud Univeristy phone, or your private phone. If you want to change the chosen login method, for example because you have a new phone, do this in the Office portal as well.