Because we use MS office and all of the software is available in a browser session. Currently each user can access their email , office programs (excel , word, powerpoint) and one drive all through a browser on any machine, by logging into www.office.com.
Add your email address and password to the authentication window
Please only add your credentials Where you see "STS.designmuseum.org" , this is our work authentication service. When on the internet using Office 365 you should never add your work password UNLESS you see this box
This is what you should see on logging into the portal. You can then click on any application and it will create a new browser tab.