Only apps from the Windows Store can be installed on Windows RT. If you have a subscription to Office, such as part of Office 365, you won’t be able to install it on your Windows RT device.
For instance, if you try to install a Microsoft Office 365 suite from the My Account page, you will first see this message:
Clicking Install on the page will then show this error:
Note Windows RT comes with Office Home and Student 2013 RT, which provides you with touch-optimized desktop versions of the new Microsoft Word, Excel, PowerPoint and OneNote.