Admob interstitial ad not showing up

I am having problems with Admob interstitial ads on android. I amm using the GoogleMobileAdsDemoScript from here. I changed it up a bit and deleted things I don´t need. I don´t want to paste the whole thing here so here is my RequestInterstitial().

 public void RequestInterstitial()
     {
         // These ad units are configured to always serve test ads.
 #if UNITY_EDITOR
         string adUnitId = "unused";
 #elif UNITY_ANDROID
         string adUnitId = "Don´t want to share this";
 #elif UNITY_IPHONE
         string adUnitId = "INSERT_HERE";
 #else
         string adUnitId = "unexpected_platform";
 #endif
 
         // Create an interstitial.
         this.interstitial = new InterstitialAd(adUnitId);
 
         // Register for ad events.
         this.interstitial.OnAdLoaded += this.HandleInterstitialLoaded;
         this.interstitial.OnAdFailedToLoad += this.HandleInterstitialFailedToLoad;
         this.interstitial.OnAdOpening += this.HandleInterstitialOpened;
         this.interstitial.OnAdClosed += this.HandleInterstitialClosed;
         this.interstitial.OnAdLeavingApplication += this.HandleInterstitialLeftApplication;
 
         // Load an interstitial ad.
         this.interstitial.LoadAd(this.CreateAdRequest());
     }

and here is the showinterstitial method.

 public void ShowInterstitial()
     {
         if (this.interstitial.IsLoaded())
         {
             this.interstitial.Show();
         }
         else
         {
             MonoBehaviour.print("Interstitial is not ready yet");
         }
     }

Here I am calling the interstitial ad.

  void OnTriggerEnter(Collider other)
     {
         if (other.gameObject.tag == "ObstaclesLeft" || other.gameObject.tag == "ObstaclesRight")
         {
             Die();
 
         }
     }
 
      void Die() 
             {
                 GoogleMobileAdsDemoScript.Instance.RequestInterstitial();
                 GoogleMobileAdsDemoScript.Instance.ShowInterstitial();
                 menuPanel.gameObject.SetActive(true);
                 startPanel.gameObject.SetActive(false);
                 fadeInPanel.gameObject.SetActive(false);
                 Time.timeScale = 0;       
             }

I am in fact getting thee console message ("Dummy ShowInterstitial") but when I run the game on my phone the ad doesn´t show up even if I call the method when the game starts or something. I have that feeling like I am missing something since I only followed that tutorial and that too is a bit outdated

If there is a possibility that there is just no ads available at the time for like couple hours now how do I use the test ads instead?