To register for Stukent courseware (textbooks and simulations), you must contact your instructor for a course invite link. This invitation link will allow you to correctly register to the proper course, even if you've created an account in the past.
Your instructor will have this link shared with the course and may have included it in your class syllabus or emailed it out. Please check with your instructor to receive this link.
Once you have received the invite, you will be able to follow the click-through link and register/create an account.
Higher Education students -- After your new account has been created, you will be able to purchase the courseware needed for your class. Which can be done in one of two ways: