In order to take pictures, you have to pick up empty polaroids around the map, the polaroids can be red, white, blue, or purple. Typically they are on a table or countertop. There is a limited number of polaroids around the map, so you have to be careful not to waste them. (And if you do run out of polaroids, there is a menu button on your left wrist.)
The camera has 5 different settings, flash (yellow), stun (red), teleport (white), reveal (purple), and barrier (blue). When you change modes, there should be a number in the colored square indicating how many polaroids you have in that setting. I hope that helps!
Also, what headset are you using? I only tested with the Quest 2.
EDIT: The camera has a 6th setting which is X-Ray. This is for those who might get scared easily and want to know where the ghosts are at all times.