Webdav. I can reach the NAS when trying to map but doesn't accept username

So configured the NAS to activate WebDav, just in case of need I enabled the port forwarding in the router for ports 80 and 443 against the internal IP of the NAS.
The next step was to go with the dashboard to one of the shares to enable WebDav access to it.

When in a remote machine from the public internet I try to map a network drive I see it can reach it… but returns back error 1920 (no access to file) which means the user has no authority to access the share.

Ideas? Share is created, webdav permission activated for NAS and share against that user and ports forwarded. Plex server for example is working perfectly on the NAS
Command used is the normal one: net use Z: \**.ddns.net\share_name /user:user_name user_password

Perhaps the following article will be able to assist:

https://support.wdc.com/knowledgebase/answer.aspx?ID=16497#WebDAVTS