Using the NextCloud calendar with calcurse-caldav

I’m trying to use calcurse-caldav with NextCloud and am having trouble getting it to work. Following a sample config that works with an independent NextCloud instance, I get the following error:

$ calcurse-caldav --init=two-way
Connecting to
error: The server at replied with HTTP status code 405 (Not
error: Allowed) while trying to access
error: av/calendars/

Any suggestions as to what I might be doing wrong?