Simple Tap Gesture to trigger Reality Composer animation

I wanted to make a very simple AR Viewer that is based on Reality Composer and RealityKit, following Apple's video "Building Apps With RealityKit" session 605. I started with an XCode Project the basic Box AR anchored to the floor, it has Reality Project loaded with a Box. That part is working fine.

I modified the RC Project and adding my own USDZ asset.

What I would like to know is just super basics:

- To be able to register Tap Gesture to trigger my Reality Setup (run animation)

- Ability to Modify Material, maybe changing color

- Adding Occlusion Material into Entity

So far I got to this by watching Apple's Video:

- I cannot seem to get a print out of where I tap on screen. I thought it would be fairly simple.

- I cannot seem to be able to see my object with Occlusion Material. I mean it is probably already in the scene but not sure where I anchor it exacly.

What is wrong exactly with my code?

import UIKit
import RealityKit

class ViewController: UIViewController {
   
    @IBOutlet var arView: ARView!
   
   
    override func viewDidLoad() {
        super.viewDidLoad()
       
        // Load the "Box" scene from the "Experience" Reality File
        let boxAnchor = try! Experience.loadBox()
       
       
        // Add the box anchor to the scene
        arView.scene.anchors.append(boxAnchor)
       
       
        // Occlusion Plane
        let planeMesh = MeshResource.generatePlane(width: 2.5, depth: 2.5)
        //let planeMesh = MeshResource.generateBox(size: 2.0)
       
        let material = OcclusionMaterial()
       
        let occlusionPlane = ModelEntity(mesh: planeMesh, materials: [material])
       
        occlusionPlane.position.y = 1.5
       
        // add to anchor
        boxAnchor.addChild(occlusionPlane)
       
       
       
       
       
    }
   
   
   
    // Hit Testing
   
    @IBAction func onTap(_ sender: UITapGestureRecognizer){
        let tapLocation = sender.location(in: arView)
       
        if let blah = arView.entity(at: tapLocation){
            print(blah.name)
        }
    }
}