Hey Mike,
Thanks for reaching out, and for the kind words about the plugin.
When it comes to displaying things by event category, you should be able to do this without issue with the core plugin, The Events Calendar, alone. For example, if you have an Event Category called “barbecue”, and your events page is example.com/events, then you can see a calendar that is made up only of events in the “barbecue” category by going to the URL example.com/events/category/barbecue.
When it comes to displaying events by specific organizers, then yes, this is only possible when the Events Calendar Pro add-on is activated. With this activated, if you have an Organizer named “Elvis”, and your website is example.com, then you can see a list of events that Elvis is organizing by going to example.com/organizer/elvis/
☝️ I hope this information helps!
Let me know if so and if there is anything else I can try to help with or elaborate on.
Cheers,
George