C++ First Person Shooter Tutorial - 2.7 - Can't compile (UE 4.16.3)

So as an exercise in troubleshooting, I looked through your code and the tutorial.

// FPS camera.
UPROPERTY(VisibleAnywhere)
UCameraComponent* FPSCameraComponent;

Is incorrect as of 4.16/4.17 and should have the type of “class” before it.
as in

// FPS camera.
UPROPERTY(VisibleAnywhere)
class UCameraComponent* FPSCameraComponent;

Give that a try, and see if it works out for you.