How to adapt this code to account for the new ARRaycastManager Component

I’m following an AR tutorial for ARFoundation, and in it, he uses Raycast. I’m finding that his original code doesn’t work for me, and that is because Raycast has been moved to a new component, supposedly. I now know that I need to use ARRayCastManager. The problem is that I’m getting errors due to not properly referencing the ArOrigin after my attempt to adjust the code to account for the ARRayCastManager. I have a feeling I’m doing something very wrong. I’m a complete beginner following this tutorial to the letter; so I got thrown off, and am wondering if someone can help me tweak this script so that it references the ArOrigin while also making use of the ARRayCastManager. Here is my script, and this is the tutorial I’m following. Thank you so much!

public class TapToPlaceObject : MonoBehaviour
{
    public GameObject placementIndicator;
    private ARSessionOrigin arOrigin;
    private ARRaycastManager raycastManager;
    private Pose placementPose;
    private bool placementPoseIsValid = false;

    // Start is called before the first frame update
    void Start()
    {

        arOrigin = FindObjectOfType<ARSessionOrigin>();
    }

    // Update is called once per frame
    void Update()
    {
        UpdatePlacementPose();
        UpdatePlacementIndicator();
    }

    private void UpdatePlacementIndicator()
    {
       if (placementPoseIsValid)
        {
            placementIndicator.SetActive(true);
            placementIndicator.transform.SetPositionAndRotation(placementPose.position, placementPose.rotation);
        }
        else
        {
            placementIndicator.SetActive(false);
        }
    }

    private void UpdatePlacementPose()
    {
        var screenCenter = Camera.current.ViewportToScreenPoint(new Vector3(0.5f, 0.5f));
        var hits = new List<ARRaycastHit>();
        raycastManager.Raycast(screenCenter, hits, TrackableType.Planes);

        placementPoseIsValid = hits.Count > 0;
        if (placementPoseIsValid)
        {
            placementPose = hits[0].pose;
        }
    }
}

bump–still stuck