This situation occurs when a new Office 365 environment is created and no Offline Address Book has been found. Log into Microsoft Office 365 as a user and wait some time before trying to link users again. The creation of the Offline Address Book (OAB) might take a couple of hours to complete.
It can take up to 24 hours for the Offline Address Book to be created and filled. The Nebula Synchronizer uses the Offline Address Book to populate the user list. Be patient & try again soon!
The following Microsoft Office 365 plans are supported; (Business Premium, Business Essentials, Enterprise & Government plan). The Microsoft plans Home and Personal and regular Business do not have the required hosted Exchange component, meaning these types of plans can not be used with the Nebula Synchronizer. For more information on the difference between pricing plans click here.
To successfully use the Nebula Synchronizer on (hosted) Microsoft Exchange environments your configuration needs to be setup correctly so it can use the auto discovery function. Please use the following Microsoft page to verify your setup.
The Nebula Synchronizer is using the Exchange Web Service (EWS) to communicate with your Microsoft Exchange Calendar. This is available in Exchange 2010 SP2 and higher. If you have a lower version of your hosting partner is using a lower version than Exchange 2010 SP2, the Nebula Synchronizer can not connect to your environment.