Navigate to the Don Johnston tools website.

 Login as a Don Johnston tool admin who is also a Google admin for the OU. 

Select Manage Students.

Select Organizational Units

Click on the Enable Auto Refresh Button. (two arrows in a circle with a diagonal line)

Click on, "Enable".

Click on, "Proceed".

Follow Google's steps to log into your account.

 Click on Allow.

Check Notify me, if you want to know when the sync is complete.

 Click on, "OK".