From their readme. I asked about that last night and he replied an pointed me to it. :)
Kiosk mode
Kiosk mode can be activated by a checkbox on the page. Note that there is no way out of kiosk mode (except refresh or closing the browser), and the play/pause and other controls will not be available. This is deliberate as a browser's kiosk mode it intended not to be exited or significantly modified.
It's also possible to enter kiosk mode using a permalink. First generate a Permalink, then to the end of it add &kiosk=true. Opening this link will load all of the selected displays included in the Permalink, enter kiosk mode immediately upon loading and start playing the forecast.
I didn't see IIS mentioned, but I didn't take a close look at the code. They give you a docker run command to set it up, so I converted it to a docker compose file so I can run it later. All of this is running on a Debian 12 system, so if IIS is needed, I'd wager that is if you are running a Windows setup.
I have mine embedded in Home Assistant now as an iframe using the Kiosk mode setting which works.