What is the problem you are facing. this question is more of webdev-Ubuntu problem than AEM problem.
Follow:- How do I access WebDAV in Ubuntu? - QNAP (AU)
Note: Make sure you are entering correct post number. If AEM is located on another port, use that port number instead of 4502. Also, if you are not running the content repository on your local machine, replace localhost with the respective server name or IP address.
Kautuk Sahni