IMPORTANT: Before proceeding, start directory synchronization. Follow these steps only if you're already running or have ...

IMPORTANT:  Before proceeding, start directory synchronization. Follow these steps only if you're already running or have set up directory synchronization, so that users don't lose access to %BRAND_OFFICE_365_SHORT%. After completing these steps, %BRAND_OFFICE_365_SHORT% relies on your on-premises directory to authenticate every user in your domain. Any "in cloud" users (existing users in %BRAND_OFFICE_365_SHORT% that aren't synchronized from your on-premises directory) in this domain can no longer authenticate, including admins. Ensure that you have a global admin account with the default onmicrosoft.com domain in %BRAND_OFFICE_365_SHORT% before you run directory synchronization (for example, [email protected]). You also need a local admin account to access your AD FS and WAP servers. For more information, see Set up Directory Synchronization in %BRAND_OFFICE_365_SHORT%.