Today, I tried creating a new project. It gave me the following issue:
"CS0246 The type or namespace name 'App' could not be found (are you missing a using directive or an assembly reference?"
I reinstalled VS2017 and Xamarin. It did not install the NDK, so I downloaded it and installed it. I'm not sure what else to do.
[1] https://i.stack.imgur.com/uXRiL.jpg "reference"