Accessing your virtual machines can have various procedures depending on what you have selected as your external network. Read the correct guide in the section with the same name as your external network.
ntnu-global
If you have global IPv4 addresses on your virtual machine you should be able to communicate with the virtual machine globally. That means that you should be able to contact the virtual machine over SSH (if it is linux) or Remote desktop (if it is windows) from the whole world, as long as the security-groups your machine is a part of are configured correctly.
It is smart to limit who is able to connect to your machines over these protocols, as the internet is regularly scanned to discover hosts communicating with SSH or RDP (Remote Desktop Protocol).
ntnu-internal
Addresses in this network are available troughout NTNU, but not in the rest of the world. That means that if your client are on a NTNU network you can contact it directly similar as if the virtual machine is in the ntnu-global network.
If you want access to your machines from home you would need to connect to the NTNU VPN service first.
How to log in
For more detailed info about how to login to a Linux or Windows VM, read here.
Whatever you do, do NOT rely on using the web console as your primary access. The web console is not meant to be a stable work surface, as it has very limited functionality. It is at best just meant to be a "window", so you can see what's going on during boot etc.