You're trying to create an account or join an Spark course, but you don't have a course key.
LMS-Integrated Course
You do not need a course key if Spark is integrated with a Learning Management System (LMS) like Canvas, Moodle, or Blackboard.
Self-Study Course
Important Use Spark for self-study only if you do not have a teacher and you are not
learning English in a school.
Other
Ask your teacher how to join the course.