Putting something after example.com/index.php will cause problems. For instance: example.com/index.php/index.php or example.com/index.php/abc will not throw you a 404 error
The /<something> that appears after a file, such as /index.php (duplicated) and /abc in the above examples is called additional pathname information (path-info). Whether this is ...
personally I think of webdav as being an obsolete protocol, and generally there are newer, easier tools for sharing files securely. I like syncthing
You could combine the webdav module with apache's Authentication and Authorization modules to achieve user and group level access to specific webdav directories as described in this tutorial: