If Office 365 is being used with existing installations of Outlook 2010 or 2013, Outlook will need to be configured to enable access to Office 365 online services.
However, when Office 365 ProPlus provides the Outlook client, users will just need to provide their Office 365 email address when first starting Outlook.
Outlook should then be automatically configured for use with Office 365, provided that all the required DNS records have been set up.