What happens when Coderpad creates an interview session?

I am trying to understand on a high level how a system like coderpad works. Everytime I use Coderpad to practice interviews with friends, it creates a session with a temporary link that both users can access to start the coding interview.

When a someone goes to the homepage they would be served the standard html page/client for the homepage. When they create an interview session they are served the html page/client for the coding pad, and there must also be a way to users to connect to the same session and for each session to be an isolated instance? Im guessing that when each user use the link, the server process their request and based on the link, it actually set up a stream connection between the users so that they can collaborate on a shared document, share video/voice.

my questions are: - how exactly is the temporary link created, and how can it be created so fast? - is my understanding of how it works correct? - Giving topics to look into that could point me in the right direction would really help