Adding intlTelInput into a Magnific popup

Question

I want to add intlTelInput to a Magnific popup but some how I keeps getting error. My error is below

Uncaught TypeError: $(...).intlTelInput is not a function

Even though I've have included all the script

    <script src="/assets/vendor/jquery/jquery.min.js"></script>
<script src="/assets/vendor/magnific-popup/jquery.magnific-popup.min.js"></script>
    <!-- Main JS -->
    <script src="/assets/js/main.js"></script>
    <script src="/assets/vendor/telinput/js/intlTelInput.js"></script>

Here is my javascript in file main.js

$('#button').click(function () {
                $.magnificPopup.open({
                    items: {
                        src: $('#your-form').html(),
                        type: 'inline',
                        callbacks: {
                            open: function () {
                            console.log("This is good");
                            $("#PhoneNumber").intlTelInput({
                                initialCountry: "us",
                                utilsScript: "/assets/vendor/telinput/js/utils.js"
                            });
                        },
                        }
                    }
                });
            });