The challenge is to search them to charge your vacuum cleaner for kill ghosts. The mechanic is that when you kill a ghost, the collectables spawn randomly around the map, is your task to find them before you been killed, and yea maybe sometimes they spawn in points where you can go, but as i said there are a lot of bugs, that i couldn't fixed because im an actual beginner. I'm trying to learn every day and do my best, btw thank you for the comment.