Teachers: https://help.explorelearning.com/en/articles/8981649-first-time-login-for-rostered-teachers
Students: https://help.explorelearning.com/en/articles/9028429-first-time-login-for-rostered-students
Product access for teachers is enabled on an account-by-account basis.
Here's a link to our Help Center that describes how to enable access for them:
https://help.explorelearning.com/en/articles/8976480-enable-product-access-for-teachers-with-accounts
Once they're given access, teachers will need to give an assignment to their students before the students can log in:
https://help.explorelearning.com/en/articles/8852867-provide-change-student-product-assignments