Auto Forward spy app

A friend of mine just got hit hard by this app. Supposedly autoforwad can install itself remotely to any phone. You buy the app for $60 and all you need is the victim’s phone number. Enter that and the app uses the internet to find the target phone and installs the spyware on the target phone. Then it’s like having a clone of their phone. You see every message, email, key stroke, social media etc. anyway he had a lot of money transferred out of his bank. The app’s website claims it can do this to iPhone. Anyone got any ideas how to protect yourself from this?