In order to join a course that requires Google or Microsoft login, students will need to register with ZenGengo by visiting https://app.zengengo.com/student/register.
After they have registered, they will be taken to the Student Portal (https://app.zengengo.com/student). Here they will be given the option to join a course.
After clicking Join a Course, students should enter the 5-letter Join Code.
The Join Code is shown in the Submission Settings panel of the desired folder if you have chosen "Require students to login with Google or Microsoft" when you created the folder:
After entering the Join Code, the students will then be able to study the course by clicking on the "Study Now" button: