Encountering multiple issues when connecting Oculus with Unity

Hello everyone, there are some issues I’m encountering with getting Oculus to work with Unity. If someone knows how to fix these, please let me know:

In the oculus software, when I run an app, the app seems to be working on the pc screen, but there’s no display in the HMD.

In Unity, in a new scene, I delete the Main camera and import the OVRCameraRig and LocalAvatar prefabs. Then I click run. Same problem as 1: no display in the HMD. Additionally, in the oculus software, I could at least see the controllers in the pc screen. In Unity, even the controllers have disappeared.

When I attach the following script to a scene:

using OVRInput;
using OVRInput.Controller;
class ... {
    public Controller controller;
    void Start() {...}}

I get the error

A 'using namespace' directive can only be applied to namespaces; 
'OVRInput.Controller' is a type not a namespace. Consider a 'using static' directive instead
A 'using namespace' directive can only be applied to namespaces; 'OVRInput' is a type not a namespace. Consider a 'using static' directive instead
The type or namespace name 'Controller' could not be found (are you missing a using directive or an assembly reference?)

Followed by another couple dozen errors like:

'OVRPlugin' does not contain a definition for '[Some class name]'

I have imported both OculusUtilities and the Oculus Asset in my project, so I can’t guess the cause of these errors.
By the way, I’m using Boot Camp Assistant to run Windows on a Mac.

Could you please paste your skript, as it seems, that you are mixing up “using” , which refers to namespaces and types, which are no namespaces as your error states.