Hi, Jenq. Thanks for your interest in our plugin suite.
We do not have any demo of the wp-admin area to provide you with.
We use our easy-breezy Refund Policy for such requests so you can buy one or many of our add-ons and thoroughly test them.
If I’m understanding your needs, you could use PRO’s Additional Fields to create a URL field for the event’s Etix link and then it would appear automatically within the Event Details meta box on the Single Event page.
Or you could just add your own custom field and then output it (such as via a shortcode) using one of the action hooks on the Single Event page (or this extension makes that easier: https://theeventscalendar.com/extensions/calendar-widget-areas/)
I hope this info helps. Let me know if you have any follow-up questions.