Hi @penono007 !
In the pro version, there’s the option to override templates and add in things like a list of categories for an event, for example the default template:
https://eventcalendarnewsletter.com/events-calendar-shortcode-pro-options/#customize-default
Then use something like get_categories() to get and display the categories.
Otherwise you’d need to do some more advanced customization with a filter to change the output, or change the plugin code itself (not recommended, since you would lose your changes when an update is released).
Cheers!