During registration of your Student Kit you will be asked to select your role: Student or Educator/Parent. Since the differences are not obvious, here you can see the main differences.
Both of these enrollment methods will grant you access to all the lessons but the small difference is that the Student account has "Further notes" (snippets of extra information for students who want to learn more about the subject they are currently reading about) and the Educator account has "Teacher notes" (tips and tricks that particular lesson.
If you wish to use the kit yourself in order to learn programming and electronics, the best role for you to choose is Student. Especially for minors who don't use email address to register with. When choosing student, you will be given generated log in credentials that you need to store or remember in order to log in the next time. In case of loss, you can contact arduino support to recover it.
If you are using the kit to teach at home or students remotely, you should enroll as an educator/parent. Doing so, you can access with your own Arduino account (linked to your email address), and can easily re-set your password here in case you lose it. You can also choose to enroll as an educator/parent even if you are an adult using the kit to learn yourself, if it is more convenient to log in with your email (Arduino account).