Effective summer of 2025, GCE is moving to require Multi-Factor Authentication (MFA) for all resources. To accomplish this, you must enroll in Duo MFA. As resources switch to using CELS MFA, you will be unable to authenticate unless you have already enrolled.
Step one: Get a GCE account! Any CELS services requiring MFA generally requires you to have a CELS account with access to GCE. You can do that here.