When trying to load the Outlook Web App on a Chromebook you'll find that you can only access the 'light' version. It's pretty easy to fix, you just need to spoof the user agent.
On a regular desktop computer launch Chrome and type chrome://version in the address bar. Find and copy the user agent string.
On your Chromebook install the User-Agent Switcher extension. After this installs click the icon and choose Settings. Enter a new customer user agent - name something like 'Chrome Desktop', the user agent string is the one you copied from a desktop PC above, group is Chrome, type is replace and enter a character or two for the indicator flag.
Next click the Permanent Spoof list tab (still in User-Agent Switcher) and enter the domain of your outlook site (i.e. outlook.mycorp.com) and choose the user agent we just created from the drop down list (i.e. 'Chrome Desktop').
Finally log out of Outlook Web Access. You should now be able to uncheck the 'light' experience and get the full version of the Outlook Web App.