To bring the Outlook address book into Zoho CRM contacts, you have to download the Outlook plug-in from Setup > Marketplace > Other > Plug-in for Microsoft Outlook page. Unzip the Zoho_CRM_Plug-in_for_Microsoft_Outlook.zip file. This will have the Zoho_CRM_Plug-in_for_Microsoft_Outlook.pkg file. Double click the file and follow the installer instructions to install the application.