The below article contains information about how to troubleshoot problems with signing in to Office apps for Mac, iPad, iPhone, or iPod Touch by using single sign-on. It provides resources for IT administrators to address reports on Active Directory Federation Services (AD FS) issues that are specific to Office for Apple iOS and Mac platforms.
For the latest information: Outlook for Mac & Devices Known Issues
Knowledge Base Article: http://support.microsoft.com/kb/3015526