I have a problem with the following $_POST. As you see from the code once the radioButton has value YES and you press submit you are redirected to the page where I put  "IdCantiere" = (value random) and? myInput = which would be the $_POST that does not work for me.
The redirect refers to the affidatario.php page in which I make the $_GET of both variables.
executing a var_dump($_GET) the only thing that finds is idCantiere. How can I get the value of myInput?
I place my code and some screens
<html>
<body>
<fieldset>
    <strong>Vuoi inserire un affidatario?</strong>
    <form action="../affidatario.php?idCantiere=<?php echo $idCantiere?>" method="POST" name="prova" onsubmit="return controlla();">
        SI<input type="radio" name="scelta" value="si" />
   <label name="myLabel" id="myLabel" style="display: none;">Ragione Sociale Affidataria</label><input type="text" id="myInput" style="display: none;"><br>
  NO<input type="radio" name="scelta" value="no" /><br />
        <button type="submit">INVIA</button>
    </form>
</fieldset>
<?php 
$myInput=$_POST["myInput"];
?>
<script language="javascript">
   function controlla() {
        console.log("oie");
        x = document.prova;
        if (x.scelta.value == "si") {
            window.location.href = '../affidatario.php?idCantiere=<?php echo $idCantiere?>?myInput=<?php echo $myInput?>'
            return false;
        }
        if (x.scelta.value == "no") {
            alert("Hai risposto no");
            window.location.href = '../inserimentoCantiere.php'
            return false;
        }
    }
 
    document.querySelectorAll('input[name="scelta"').forEach(function(a) {
        a.addEventListener("change", function() {
            let textBox = document.getElementById("myLabel");
            if (textBox) textBox.style.display = this.value === "si" ? "block" : "none";
        })
    });
     document.querySelectorAll('input[name="scelta"').forEach(function(a) {
        a.addEventListener("change", function() {
            let textBox = document.getElementById("myInput");
            if (textBox) textBox.style.display = this.value === "si" ? "block" : "none";
        })
    });
</script>
</body>
</html><?php 
 $idCantiere = $_GET["idCantiere"];
 date_default_timezone_set('Europe/Rome');
    $date = date('Y-m-d');
 chdir("../../../../../Archivio/Cantieri");
 opendir(".");
  $myInput = $_GET["myInput"];
 if(mkdir("../../../../Archivio/Cantieri/".$date."_".$myInput))
 {
 echo "Cartella account creata con successo! :D";
 }
 echo "<script type='text/javascript'>alert(myInput);</script>";
var_dump($_GET);
 session_start();
    if(!isset($_SESSION["username"])){
     header('location: ../../../index.php');
    }
    else
    {
 
?>
 
     
    