The member will receive a text to his phone saying that the teacher added him/her to the group. They will also receive a link to the site and the temporary password using which they can sign in. They will continue to receive the updates the teacher makes to her/his class as Texts even if they did not sign in. They can choose to sign-in on the website or by downloading the app.
Once they sign in with the phone number and the temporary password sent to the text, they will have access to the class and they can respond to the updates, messages and communicate with the teacher/admins on the app.
Please view - Parent - Signing in with phone number