Showing Admob Banner Ad in scene?

I have two scenes. Menu and Game. I want a banner ad to always stay on screen only and only during the game scene. How can I do this?

This is the ad script

 public class AdManager : MonoBehaviour {
     public static AdManager Instance{ set; get; }
     public string bannerId;
     public string videoId;
 
     // Use this for initialization
     private void Start () {
         Instance = this;
         DontDestroyOnLoad (gameObject);
         #if UNITY_EDITOR
         #elif UNITY_ANDROID
         Admob.Instance().setTesting(true);
         Admob.Instance ().initAdmob (bannerId, videoId);
         #endif
     }
     
     // Update is called once per frame
     void Update () {
         
     }
 
     public void ShowBanner(){
         #if UNITY_EDITOR
         #elif UNITY_ANDROID
         Admob.Instance ().showBannerRelative (AdSize.Banner, AdPosition.TOP_CENTER, 0);
         #endif
     }
 }

To show the banner I am using : AdManager.Instance.ShowBanner ();

Thank You