Make an enemy generator

I'm trying to make an endless game where the player can only move in 3 specific lanes (up, mid, and down) and try to survive the enemies coming from these lanes. The main problem it's i don't know how to make an enemy generator...

This is the player movement:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Movement : MonoBehaviour
 {
     GameObject SpawnCentrale;
     GameObject SpawnBasso;
     GameObject SpawnAlto;
 
     // Start is called before the first frame update
     void Start()
     {
         
         SpawnCentrale = GameObject.FindWithTag("Spawn1");
         SpawnBasso = GameObject.FindWithTag("Spawn2");
         SpawnAlto = GameObject.FindWithTag("Spawn3");
         
         transform.position = GameObject.Find("Spawn1").transform.position;
 
     }
 
 
     // Update is called once per frame
     void Update()
     {
         if (Input.GetKeyDown(KeyCode.W) && transform.position == SpawnCentrale.transform.position)
         {
             transform.position = GameObject.Find("Spawn3").transform.position;
         }
 
         if (Input.GetKeyDown(KeyCode.W) && transform.position == SpawnBasso.transform.position)
         {
             transform.position = GameObject.Find("Spawn1").transform.position;
         }
 
         if (Input.GetKeyDown(KeyCode.S) && transform.position == SpawnCentrale.transform.position)
         {
             transform.position = GameObject.Find("Spawn2").transform.position;
         }
 
         if (Input.GetKeyDown(KeyCode.S) && transform.position == SpawnAlto.transform.position)
         {
             transform.position = GameObject.Find("Spawn1").transform.position;
         }
 
     }
 
 }

This is the enemy movement (for just one lane):

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class Enemy : MonoBehaviour
 {
     public float speed = 5.0f;
     private Rigidbody2D rb;
     GameObject CancellaNemici;
     // Start is called before the first frame update
     void Start()
     {
         rb = this.GetComponent<Rigidbody2D>();
         rb.velocity = new Vector2(-speed, 0);
         CancellaNemici = GameObject.FindWithTag("DeleteEnemy");
     }
 
     // Update is called once per frame
     void Update()
     {
         if (transform.position.x < CancellaNemici.transform.position.x){
             Destroy(this.gameObject);
         }
         
             
         
     }
 }

And this is my attempt to make an enemy generator, but it's not working:

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class DeployEnemy : MonoBehaviour
 {
     public GameObject EnemyPrefab;
     GameObject EnemySpawn;
 
     void Start()
     {
         StartCoroutine(SpawnObjects());
         EnemySpawn = GameObject.FindWithTag("SpawnEnemy");
     }
     IEnumerator SpawnObjects()
     {
         while (true)
         {
             Instantiate(EnemyPrefab, EnemySpawn.transform.position, Quaternion.identity);
             yield return new WaitForSeconds(3.0f);
         }
     }
 
 }

I'm new to game development and programming in general so i'm really lost >_<