Scam/scary app that shouldn’t be on the app store

So I got an ad to an app on instagram. Name of the app is “Phone tracker app GPS locator” by “ozlem demirci”. It says in the description that once you download the app you type in the phone number of the person you want to stalk and it tells you the location of this person without their consent. It says that it finds the location via text message. I don’t know how this works. The person doesn’t even have to download the app! I find this really creepy. How is this even allowed? Is this even technically possible? No idea.