How to start an animation of the object itself by trigger enter in #C?

Hey folks, I am making a game where the main character can encounter bushes and branches. I intended to start an animation of these branches that makes them wave during an encounter with the player. I now have 2 scripts. one attached to the branch and one on the polygon collider which is on the branch. I am asking this question because I wasn't able to find this problem in #C

The branch scripts looks like this:

 using UnityEngine;
 using System.Collections;
 public class MovingBranch: MonoBehaviour {
     
     public bool PlayAnimation = false;
     
     
     void Start () {    
         
     }
     
     
     void Update () {
         if(PlayAnimation){
             // Whatever function or code you write to start the animation
             // or however you want to do the animation}
         }
     }
 }
 

And the script attached on the polygon collider looks like this:

 using UnityEngine;
 using System.Collections;
 
 public class Box: MonoBehaviour {
     // Make sure you have the Branch Object
     public GameObject Branch;
     // The Script of the Branch;
     private MovingBranch movingbranch;
     
     
     void Start () {    
         // This will get the script and set the trainscript
         movingbranch= Branch.GetComponent("MovingBranch") as MovingBranch ;
     }
     
     // Update is called once per frame
     void Update () {
         
     }
     
     void OnTriggerEnter(Collider collision){
         if(collision.gameObject.tag == "Player"){
             movingbranch.PlayAnimation = true;
         }
     }
 }

I converted a existing script into my project but it simply doesn't work even though there are no errors. I don't know why the animation is not started when being touched by the main player? I am a beginner in scripting.

If somebody can point me into the right direction that would be really helpful :)