how can I make an Ajax call instead of post printing the waybill from WordPress on my php website?

<form id="print-shipping-label-form">
    <input type="hidden" name="shipping_id" value="<?php echo $result_wpid_shipping['ID']; ?>">
    <input type="hidden" name="api_key" value="ce312203c06e8bda7157c408fbac54c4">
    <button type="submit" class="btn btn-danger">Drukuj list przewozowy</button>
</form>

<script>
    document.addEventListener('DOMContentLoaded', function() {
        var printShippingLabelForm = document.getElementById('print-shipping-label-form');
        
        if (printShippingLabelForm) {
            printShippingLabelForm.addEventListener('submit', function(event) {
                event.preventDefault(); // Zatrzymaj domyślne zachowanie formularza
                
                var formData = new FormData(printShippingLabelForm);
                var url = 'https://torebki-fabiola.pl/?flexible_shipping_get_label=' + formData.get('shipping_id') + '&apikey=' + formData.get('api_key');
                
                // Wykonaj żądanie AJAX
                fetch(url, { method: 'POST' })
                    .then(function(response) {
                        return response.text();
                    })
                    .then(function(responseText) {
                        // Obsłuż odpowiedź z serwera, np. otwórz ją w nowym oknie.
                        window.open(responseText, '_blank');
                    })
                    .catch(function(error) {
                        console.log('Wystąpił błąd podczas wykonywania żądania AJAX: ' + error);
                    });
            });
        }
    });
</script>

I try to fix problem with this code