A Nextcloud storage is a specialized WebDAV storage, with optimizations for Nextcloud-Nextcloud communication. See the WebDAV documentation to learn how to configure a Nextcloud external storage.
When filling in the URL field, use the path to the root of the Nextcloud
installation, rather than the path to the WebDAV endpoint. So, for a server at
https://example.com/nextcloud and not
See Configuring External Storage (GUI) for additional mount options and information.
See External Storage authentication mechanisms for more information on authentication schemes.