To confirm that directory synchronization is provisioning users, groups, and contacts from your on-premises Active Directory ...

To confirm that directory synchronization is provisioning users, groups, and contacts from your on-premises Active Directory to %BRAND_OFFICE_365_SHORT%, see Verify directory synchronization. If you're having problems getting directory synchronization to work properly, check out Fixing problems with directory synchronization for %BRAND_OFFICE_365_SHORT%.