The Informatics Remote Desktop gives you a DICE graphical login, displaying on your computer.
This page explains how to use Remote Desktop on a Mac.
It tells you how to install the client, then configure it, then connect to DICE. Installing and configuring the client only have to be done once.
You will need to use the University VPN. If you don't, you won't get access to the Remote Desktop service - unless your computer is already on the University of Edinburgh network (for example in an office or a computing lab).