Using POST and WebRequest in Unity

Hey!
I have a mini-system with MySQL and PHP and I need to connect it with Unity, for login, save high scores, etc. I used the example from here: https://docs.unity3d.com/ScriptReference/Networking.UnityWebRequest.Post.html
But when I call the Login method from a Canvas button, the system returns a successful result (using Debug.Log function), but the PHP file doesn't detect POST from Unity. Now, I guess the problem is on the PHP file, but I didn't find any issue with POST logic, so I can't confirm this statement.
I'm using XAMPP to create a server with MySQL and PHP. Here is my class for connection using System.Collections; using System.Collections.Generic; using UnityEngine; using UnityEngine.UI; using UnityEngine.SceneManagement; using UnityEngine.Networking; public class Server : MonoBehaviour { public InputField username; public InputField password; public void Login() { StartCoroutine(Upload()); } IEnumerator Upload() { WWWForm form = new WWWForm(); form.AddField("username", username.text); form.AddField("password", password.text); UnityWebRequest www = UnityWebRequest.Post("http://localhost/school-system/unity/index.php", form); yield return www.SendWebRequest(); if (www.result != UnityWebRequest.Result.Success) { Debug.Log(www.error); } else { Debug.Log("Form upload complete!"); } } } And here is my index.php (I'm not using any hash function for passwords, because the system at moment is only for tests)