Integration Calendly on a Button Click

Dear Forum,
i want to put calendly on a button on a clients site

Calendly offers this code:
How can i trigger the popup on a button click?

 <!-- Calendly Link-Widget Beginn -->
<link href="https://assets.calendly.com/assets/external/widget.css" rel="stylesheet">
<script src="https://assets.calendly.com/assets/external/widget.js" type="text/javascript"></script>
<a href="" onclick="Calendly.initPopupWidget({url: 'https://calendly.com/smilikeberlin/erstberatung-praxis-berlin'});return false;">Zeitplan Zeitfenster</a>
<!-- Calendly Link-Widget Ende -->

Please don’t cross post. I answered your question in the other post you made.