[Question] Unity C# Set a Player Class and refence issue

Hi there you all I have been working to understand this and work on it but I couldnt do it so here I am asking for help. There is 3 Class for my game in UI (warrior , archer ,wizard) , all of them buttons and toggle in them , when you click the button it actives the toggle in group and player can know which class he chosed. The issue is I have another scene for Character and Inventory but I can not reference the toggle and so can not get data which class player chosed.

 public class ToggleScript : MonoBehaviour
 {
     public Button currentButton;
     public Toggle currentToggle;
     public AudioSource buttonclicksound;
     public ToggleGroup ToggleGroup;
     public static string classname;
     public static ToggleScript toggleScript;

     private void Start()
     {
         
         buttonclicksound.GetComponent<AudioSource>();
         currentButton.GetComponent<Button>();
         currentToggle.GetComponent<Toggle>();
         currentButton.onClick.AddListener(OnClick);
         ToggleGroup.GetComponent<ToggleGroup>();
     }
     public void OnClick()
     {
         Toggle selectedToggle = ToggleGroup.ActiveToggles().FirstOrDefault();
         if (selectedToggle != null)
             Debug.Log(selectedToggle, selectedToggle);
 
         buttonclicksound.Play();
         currentToggle.isOn = true;
         classname = selectedToggle.ToString();
 
     }

So here is toggle script I currently use I know its not clean that much but It keeps work selectedToggle is the player last chosed toggle and It shows in console So I transfer it to him string and put it in static public string so I could take this string from another scene in script and I can detect what player chose but I cant do the reference.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 using UnityEngine.UI;
 
 public class SetCharacter : MonoBehaviour
 {
     string name;
     public void Start()
     {
         name = ToggleScript.classname;
         Debug.Log(name);
     }
 
 }
 

It doesnt work I get error of unity object reference not set to an instance of an object , any ideas or solution ?