In AirWatch 9.0, you receive the error "device not whitelisted" when you attempt to enroll an Android device. This was functional prior to upgrading to AirWatch 9.0.
Navigate to Settings > Devices & Users > General > Enrollment > Restrictions. If you have any device restriction that contains Android devices, the restriction policy must either be disabled, or the Android setting must be the last setting configured in the whitelist/blacklist policy. If any Android model is whitelisted/blacklisted in the middle of the policy, enrollment will not complete successfully for Android devices.
This has been resolved in AirWatch 9.1.