I would like to trigger a popup by clicking on specific text

Hi,

I have tried this solution on Klaviyo website but this is not working at somehow. I don't have the expertise to code I understand it a bit but I don't know why It is not working.

I would like to have a pop-up which is triggered by a text. The pop-up gives more explanation to the customer.

<button class="klaviyo_form_trigger">Wat is je maat?</button>

<script type="text/javascript">
	document.querySelector('.klaviyo_form_trigger').addEventListener('click', function (){
		window._klOnsite = window._klOnsite || []; 
		window._klOnsite.push(['openForm', 'TKGULa']);
	});
</script>

I guess I do something wrong but I don't know what.