I am just a little bit confused, while reading the documentation, first i thought the Calendar App gives the endpoint, but the github documentation says it is just an interface for the server-api, but i couldn’t find it mentioned in the Documentation: https://docs.nextcloud.com/server/18/developer_manual/index.html
Nextcloud does have a CalDAV/CardDAV implementation accessible at the base URL endpoint: https://sub.example.com/remote.php/dav or https://example.com/nextcloud/remote.php/dav
depending on your installation.
For anyone reading, do note the apache .htaccess template in the documentation is incomplete as of Nextcloud 20 at the time of writing, resulting in setup warnings for webfinger and nodeinfo. Visit this thread for more info.