Make your AdvCalendar page insert the Advcalendar plugin using the page view

Then change to list view and create new Calendar Categories records(if you need this feature)

You can easily configure plugin in Web>Temlate> Constant Editor>PLUGIN.ADVCALENDAR

In List view you can see your records and you can also add manually Calendar items this way.

You can also set storage of records to page where your FE users are kept (so you get proper list of users for Owner (who created record) when manually creating calendar items.

Hit the FE and see your calendar