Certain apps in the Google Apps Marketplace will require API access on the domain to function properly.
It’s easy to enable API access for Google Apps as an admin in just a few steps.
Enabling API Access for Google Apps
1 Go to the Google Apps Admin area
2 Go to the Security area in Admin
3 Click on API Reference for more options
4 Enale API Access for Google Apps: Ensure that “Enable API Access” is checked and click Save if needed.