Presence detection not detecting beginner problem

Hello HA team
Could someone please advice me how to setup person detection in HA.
I have only got started with HA and even basic not come easy.
I have one of the newest version and looks there is some kind of build in feature for detection
which I manage to set in configuration panel - persons option.
Unfortunately my badge on home screen HA shows UNK.
Do I need to install or configure extra components?
Thank you