This article explains what features the guardian account has as well as the difference between a primary guardian account and a regular guardian account.
All guardians will have be able to schedule and reschedule classes, view your child’s assignments, and view your child’s over all progress. As a guardian, you cannot join classes from your account view or work on homework directly, only students can do this.

Important: You can have as many guardian accounts connected to a student as you want, but only one primary guardian account. Only the primary guardian account has access to billing.
Primary Guardian
Your primary guardian account is the email account that you originally signed up with. Only the primary guardian will have access to billing, where they can add subjects/classes, change their credit card information, and cancel their subscription.