Nautilus supports WebDAV, but doesn't accept the webdav:// URL scheme (KDE KIO/Dolphin syntax)
Copied from https://bugzilla.gnome.org/show_bug.cgi?id=768814
Nautilus loads WebDAV servers with URIs such as:
While Dolphin prefer this instead:
webdav://localhost:42427/Backup/
Developers of programs such as Cryptomator shouldn't have to test what file manager you have installed to load their UIRs correctly (see https://github.com/cryptomator/cryptomator/issues/307).
Nautilus could support webdav:// by itself, or convert it automatically to dav:// in the address bar with the necessary changes.
Or you could get together with the KDE developers to agree upon a standard URI for webDAV scheme to avoid such incompatibilities.