Grant Google Permissions
Click Allow Registration next to the error message.
Click Select Google Permissions.
A new window opens, showing the permissions NGLSync needs to access your Google Classroom class.
Select all permissions, then click Continue.
Students in your Google Classroom can now access their learning platform through NGLSync.
Unlink Google Classroom
Click Edit under Google Classroom Registration.
Click Unlink Google Classroom.
Add students to your NGLSync course.
You can give students a link to enroll themselves, or manually enroll each student.