If you are on NC 13.0.0, there can be some issues with caching:
(also clear your browser cache or try to access via private mode)
You can also try to disable and enable the app via the app store. If the version is not up to date, it will get the latest version.
Nextcloud ships its own dav-implementation (based on sabre-dav), it is not required to install it separately. You shouldn’t activate other webdav stuff in your Nextcloud folder, it normally brings everything you need.
There can be some more locations where the old path is stored:
Before you modify anything manually (especially the database), make sure you have a full backup that you can get back in case something does not work.