Windows 10 (64 bit) black screen

I’m going through this tutorial

https://library.vuforia.com/articles/Solution/Getting-Started-with-Vuforia-for-Unity-Development#How-To-Setup-a-Simple-Unity-Project

But when I run my game all I see is a black screen. Can anyone tell me why?

Click the AR camera then click the “Open Vuforia configuration” button in the property inspector. Scroll down and untick the “Disable Vuforia Play Mode”