someone has already tried this app and can explain how to set it? I was interested in being able to access the camera of a mobile phone

Hi, developer of the app here.
when you start the app, it displays the ip and the port of your device at the top.
you can access the camera via http://<ip of your device>:<port>/cam It takes a new picture on every request.
Take a look into the demo sitemap of openHAB to find out, how to access the picture in your sitemap.

I will release a new version of the app and share some examples on my website asap.