April 2024 App Update has a glitch
The app (which is the only thing that makes the camera accessible) was updated (April 2024). To access it you need to agree the T&Cs. On some phones (like my Samsung) you cannot see the box to tick to say you have read them, so cannot use the app. Luckily, I have another device where you can see where the box is. I ticked the general area where the box was on my phone and it now works. Maybe check an update on some common phones before issuing?