Before any monitored interview you walk through a system check. It is not a formality — each test corresponds to something the interview will need, and clearing them beforehand is far easier than clearing them with a clock running.
What it tests
Camera — that one exists, that permission is granted, and that it produces a picture.
Microphone — the same, plus that it is picking up sound. Speak and watch the level move.
Network — that your connection is stable enough for live audio and video.
Browser — that yours supports what this interview needs. Chrome and Edge are the safest choices; Safari and Firefox work for most stages.
Displays — where the interview requires a single screen, that only one is connected.
Running it early
The link works before your interview begins, and doing the check the day before costs nothing and uses no attempt. Every problem it finds is easier to fix with time in hand.
When a check fails
The failure says what is wrong and what to do, and the remedy is one you can actually carry out from where you are. A check that suggested closing the browser you are locked inside would be no help, and the guidance is written with that in mind.
Most failures are a browser permission refused once and now remembered. See camera and microphone.
Continuing with a warning
Some findings are warnings rather than blocks — a slightly slow connection, a second display where one is only preferred. You can continue, and the warning is recorded so nobody later mistakes a known condition for something you did.