From the troubleshooting guide:
When you troubleshoot activation of Android for Work devices, check the following:
- Make sure the device supports Android for Work. For more information, visit https://support.google.com/work/android/answer/6174145 to read article 6174145.
- Make sure that there is an available license and the activation type is set to Work and personal - user privacy (Android for Work).
- To use the Work and personal - user privacy (Android for Work) activation type, devices must be running Android OS version 5.0 (Lollipop) or later.
- Make sure that the user account in BES12 has the same email address as the one in the Google domain. If the email addresses do not match, the device will show the following error: Unable to activate device - Unsupported activation type. Look for the following in the core log file:
- ERROR AfW: Could not find user in Google domain. Aborting user creation and activation.
- ERROR job marked for quarantine due to: Unable to activate device - Unsupported activation type