What the stoplight does if you turn it off is it makes the Rollercoaster continue moving,if he didn't do that then the Rollercoaster would've stopped there and he would've got hit
Before you log in, on the Main Menu Screen there will an option to scan a QR code and it’ll do the rest for you. It’s super easy (Only downside is you have to scan every single time you want to play on your PC)