Perlin Noise world generator, instantiating smaller tiles together.

I'm referring to this YouTube video of Arend Peter Teaches: Coding Perlin Noise in Unity

In the tutorial, he uses 100x100 tile to generate the world, but I would like to use a real Terraria tile which is 16x16, if I just fit in the 16x16 .png tiles to the prefab, the world generates the prefabs with lots of gaps in between.

I'm attaching the 2 scripts used in the video:

 using UnityEngine;
 using System.Collections;
 
 public class Generator : MonoBehaviour {
     
     public GameObject dirtPrefab; 
     public GameObject grassPrefab; 
     
     int minX = -160; // affects -x length of world generation
     int maxX = 160; // affects x length of world generation
     int minY = -10; // affects -y height of world generation
     int maxY = 10;  // affects y height of world generation
     
     PerlinNoise noise;
     
     void Start ()
     {
         noise = new PerlinNoise(Random.Range(1000000,10000000));
         Regenerate();
     }
     
     private void Regenerate()
     {
         float width = dirtPrefab.transform.lossyScale.x;
         float height = dirtPrefab.transform.lossyScale.y;
         
         for (int i = minX; i < maxX; i++)
             {
             //columns (x values
             int columnHeight = 2 + noise.getNoise(i - minX, maxY - minY - 2);
 
             for(int j = minY; j < minY + columnHeight; j++)
                 {
                 //rows (y values)
                 GameObject block = (j == minY + columnHeight - 1)?grassPrefab:dirtPrefab;
 
                 Instantiate(block, new Vector2(i * width, j * height), Quaternion.identity);
                 }
             }
     }
 }

and

 using UnityEngine;
 using System.Collections;
 
 public class PerlinNoise {
     
     long seed;
     
     public PerlinNoise(long seed)
     {
         this.seed = seed;
     }
     
     private int random(long x, int range)
     {
         return (int)(((x+seed)^5) % range);
     }
     
     public int getNoise(int x, int range)
     {
         int chunkSize = 16; //affects surface smoothness
         
         float noise = 0; //affects height of generation
         
         range /= 1;
         
         while(chunkSize > 5)
         {
             int chunkIndex = x / chunkSize;
             
             float prog = (x % chunkSize) / (chunkSize * 1f);
             
             float left_random = random(chunkIndex, range);
             float right_random = random(chunkIndex + 1, range);
             
             
             noise += (1-prog) * left_random + prog * right_random;
             
             chunkSize /= 2;
             range /= 2;
             
             range = Mathf.Max(1,range);
         }
         
         return (int)Mathf.Round(noise);
     }
 }
 

What should I be looking to change within the codes?

And a brief explanation as to why would be very much appreciated!

Thank you in advance.