Your district's technology coordinator must configure your school's Google Classroom settings to allow NGLSync access.
Resolution
Give these instructions to your technology coordinator.
Go to https://admin.google.com
Click Security › Access and data control › API controls.
If NGLSync is shown in Apps pending review:
Approve NGLSync for use.
If NGLSync is not shown in Apps pending review:
Click Manage Third-Party App Access.
In Accessed Apps, click View List.
If NGLSync is marked not configured, click Change Access and follow the prompts given.