@matt216
More details about your environment are needed to know what happens.
Let’s start with the concept.
Some CALDAV Providers don’t serve any public iCAL(.ics) URL to be consumed externally. You don’t need this module if your CALDAV service can host iCAL URLs. I have no idea about baikal, but I think you know whether that service would provide iCAL or not.
MMM-CALDAV can access the CALDAV server(which would not host any public iCAL URL) to get target calendar events. Then, this module converts the event data to a real iCAL file(.ics). And this module also hosts that file as a URL accessible from the default calendar module or some iCAL consuming modules with security. MMM-CALDAV will work like a private iCAL provider service.
So, to show your event on MM, you may need both MMM-CALDAV and calendar module together.
.env file is needed to connect/authenticate CALDAV server and some security features. Calendar events are very private so I want to block the security hole on working this module. You should put .env in MMM-CALDAV directory.
So, where are you stuck now? Tell me what happens.