Do I need an app and internet on my smartphone to enable a Lamassu ATM to detect and scan my QR code? I want to send bitcoins to a friend through a Lamassu ATM. She has emailed me her request QR code and when I went to the Lamassu ATM point, after pressing on the start button and  showing the QR code on my smartphone, nothing happens. I learned that the atm is supposed to scan the QR code and send bitcoins to the request QR code after putting in cash. 
I am wondering, if I may need an app or internet on my smartphone to enable the Lamassu ATM to detect and scan the QR code on the phone screen.
You don't need internet or an app. Actually, the machine can either scan a paper QR code or a mobile phone.

The problem would either be that the QR code encodes different information than what you thought it does, or that the scanner of the ATM does not recognize the QR code on the screen. What you need to show is a Bitcoin address.

Try to set your screen to full brightness, be sure not to block any part of the screen when presenting it, and check whether the QR code actually contains a Bitcoin address, and not something else such as a private key or payment request.