Other than having ssh installed on your machine, this method has no further prerequisites for its use. You can just pick one of the login/interactive nodes, and connect to it using, for instance:
ssh username@login1.hb.hpc.rug.nl
After this you will be prompted for your password followed by the authenticator token.
If you want to launch an application with a graphical user interface, you will have to add an additional -X flag to the ssh command:
ssh -X username@interactive1.hb.hpc.rug.nl
The -X option will enable X11 Forwarding, which is necessary to be able to display graphical output from programs running on the cluster. Note that this option may be the default setting on your system. An X server should be running on your local desktop to allow graphical output. On Linux, an X server is running by default, so no further software is required for this.