Boids/Flocking Tutorial

Hello everyone. Before I begin, I just want to say how helpful everyone has been guiding me through the various pitfalls that come with learning game development in Unity. Thank you.

Currently, I am trying to expand my knowledge by creating a simple RTS and I ran into something I've never heard of before - boids. Unfortunately, when I give a move command to a group of units, they all fight over the destination vector and either clump together or, if rigid bodies, try to push the single object that occupies the destination vector out of the way. I've been scouring Google in hopes of finding some sort of tutorial on the subject, but I haven't had much luck. I was wondering if anyone has come across anything of the sort. The closest thing I found was this; however, it uses A* instead of Unity's built in pathfinding system. I am a complete novice when it comes to AI programming, so I'm not sure if A* is something I should adopt. I know there are few boid controller and flocking scripts on Unify, but I'd prefer something with a bit of explanation. Any advice would be greatly appreciated. Below is my script in its current state. Thanks again.

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 
 public class UnitInteraction : MonoBehaviour 
 {    
     bool contactMade;
     bool selected;
     
     GameObject currentSelection;
 
     Vector3 targetDestination;
     
     Shader outline;
     Shader diffuse;
     
     Ray ray;
     RaycastHit hit;
     
     List<GameObject> selectedUnits = new List<GameObject>();
 
     void Start () 
     {
         outline = Shader.Find("Outlined/Silhouetted Diffuse");
         diffuse = Shader.Find("Diffuse");
         selected = false;
     }
 
     void Update () 
     {
         ray = Camera.main.ScreenPointToRay(Input.mousePosition);
         hit = new RaycastHit();
         
         SelectUnit();
         MoveUnit();
     }
     
     void SelectUnit()
     {
         
         if(Input.GetMouseButtonDown(0))
         {
             if(Physics.Raycast(ray,out hit))
             {
                 currentSelection = hit.collider.gameObject;
                 
                 if(currentSelection.tag == "Unit")
                 {
                     if(selectedUnits.Contains(currentSelection))
                     {
                         currentSelection.renderer.material.shader = diffuse;
                         selectedUnits.Remove(currentSelection);
                         selected = false;
                     }
                     else
                     {
                         selectedUnits.Add(currentSelection);
                         currentSelection.renderer.material.shader = outline;
                         selected = true;
                     }
                     
                     currentSelection = null;
 
                 }
                 else if(hit.collider.gameObject.tag != "Unit")
                 {
                     selectedUnits.Clear();
                     renderer.material.shader = diffuse;
                 }
             }
         }
     }
     
     void MoveUnit()
     {
         if(Input.GetMouseButtonDown(1))
         {
             if(Physics.Raycast(ray,out hit))
             {
                 if(hit.collider.gameObject.tag == "Floor")
                 {
                     targetDestination = hit.point;
 
                     for(int i = 0; i < selectedUnits.Count; i++)
                     {    
                         selectedUnits[i].GetComponent<NavMeshAgent>().SetDestination(targetDestination);
                     }
                     
                 }
             }
         }
     }
 }