Office 365 is accessible on most mobile devices using the native mail client (no need for purchasing of installing apps). Microsoft provides a Mobile Phone Setup Wizard. Please follow this link.
Instructions for configuring a Driod X device can be found here on the Verizon Wireless site. When prompted to enter a server name, please enter outlook.office365.com
Blackberry instructions can be found here.
Below are instructions for setting up an iPhone or iPad