Modal with validation

Hello,

I have purchased the enfold theme and quite enjoy it. I’m trying to get a modal working and have found on the forums here, https://kriesi.at/support/topic/lightbox-for-mailchimp-form/#post-582439 how to enable modals.

In testing this works perfect, however when I try to convert the plain text button to an avia button, it fails to pop-up anymore.

The contents of the modal is a bit unique, requiring users to select the checkbox before the button contained within allows for the user to continue to the next site.

The button is:
‘CLICK HERE TO BOOK ONLINE TODAY‘

Here is the code being used:

<div id="contact"  class="white-popup narrow mfp-hide">
<div id="comp-kp7d8c3j" class="HcOXKn SxM0TO QxJLC3 comp-kp7d8c3j wixui-rich-text" data-testid="richTextElement">
<b>Please accept the following:</b>
<p>Be kind, courteous, happy. :)</p>

<script>
document.addEventListener('DOMContentLoaded', function() {
    var agreeCheckbox = document.getElementById('agreeCheckbox');
    var redirectBtn = document.getElementById('redirectBtn');

    agreeCheckbox.addEventListener('change', function() {
        redirectBtn.disabled = !agreeCheckbox.checked;
    });
});
</script>
<input type="checkbox" id="agreeCheckbox"> I agree to the terms & conditions above
<button id="redirectBtn" disabled onclick="window.location.href = 'https://somewebsite';">CONTINUE TO BOOKING</button>
</div>
</div>

Any help is greatly appreciated.
Thank you.