Assign a role to the user who registers on a form

Question

$POST = filter_var_array($_POST, FILTER_SANITIZE_STRING);

$nome = $POST['nome'];
$cognome = $POST['cognome'];
$email = $POST['email'];
$token = $POST['stripeToken'];

$nickname = $nome . ' ' . $cognome;

// Inserisce utente nel DB
$user_data = [
    'user_login' => $nickname,
    'user_pass'  => wp_generate_password (),
    'user_email'   => $email,
];
$user_id = wp_insert_user($user_data);

update_user_meta( $user_id, 'first_name', $nome);
update_user_meta( $user_id, 'last_name', $cognome);
update_user_meta( $user_id, 'last_name', $cognome);
wp_update_user( array ('ID' => $user_id, 'role' => 'editor') ) ;

Please try this code.