Hi,
Thanks for using the Events Calendar. Both Pro and the free version about the same in terms of customizations.
We have a themer’s guide that can show you how to move the template for the Event List Widget in either the free version or Pro to your theme to edit there.
https://theeventscalendar.com/knowledgebase/themers-guide/
The list widget template is found here:
the-events-calendar\views\widgets\list-widget.php
There you can add a WordPress function to get a custom field or the except or another method to add the content you would like.
That is about all we can help on customizations for both the free version and Pro as well.
Thanks