How to get the response from the server into a method?

Question

Unity

I wrote such a simple authorizer, here is the method itself hung on the button

spoiler

public class Authorization : MonoBehaviour{
    private string login;
    private string password;
    public string answer;
    public void ClickAuthorization(){
...........
        Dictionary<string,string> a = new Dictionary<string,string>();
        a.Add("login",login);
        a.Add("password",password);
        Server.Inst.SendData(a);
        //answer = Server.Inst.SendData(a);
        //Debug.Log(answer);
        }
    }

here is the script itself that sends/receives data

spoiler

public class Server: MonoBehaviour{
    public static string answer;
    public static Server Inst;
    private void Awake(){ Inst = this; }
    public void SendData(Dictionary<string,string> a){
        StartCoroutine(SendDataWWW(a));
        }
    IEnumerator SendDataWWW(Dictionary<string,string> a){
        WWWForm form = new WWWForm();
        foreach(KeyValuePair<string,string> v in a){
            form.AddField(v.Key,v.Value);
            }
        UnityWebRequest www = UnityWebRequest.Post("https://..............", form);
        yield return www.SendWebRequest();
        if (www.isNetworkError || www.isHttpError){
            answer="error";
            }else{
                answer=www.downloadHandler.text;
                }
        Debug.Log("answer server => "+answer);
        }
    }

Everything works, the data is sent to the server and the server sends a response to Debug.Log("answer server => "+answer); the correct answer comes.
The problem is that I need to get this answer in the ClickAuthorization() method itself, there I commented out how to do this, I still don’t understand ...
Tell me how can I modify my script to get the data there?