NOTE: If you do not know what this field means, then you can safely leave it empty.
An authenticator is a device or program like Google Authenticator which adds a pseudo-random element to your login process by providing a 6-8 digit number each time you login.
This portal takes advantage of this capability by providing a way (once logged in) that you can attach an Authenticator to your account. This technology was invented as it is very common for people to use weak passwords. When using an authenticator this helps to ensure that your account remains secure from brute-force or simply guesisng your password based on information someone may know about you from social media, or other online places.
When your account is created, no authenticator is added as this is not a process that we can do for you. Authenticators are essentially your secret between you and the authentication system and are unique.