Purpose

Your Atlassian Cloud account includes a WebDAV directory share. You can use this to upload large files to share with support, backup files, or data you want to import into your instance.  See Upload data via WebDAV for more information.

Cyberduck is a free FTP, SFTP, WebDAV, S3 & OpenStack Swift browser for Mac and Windows.

Solution

Download Cyberduck and use the following connection configuration:

This type of connection will be encrypted and connect to the WebDAV root directory.

• Server: instance-name.atlassian.net. Note: Please make sure you replace "instance-name.atlassian.net" by your Cloud instance name. 
• Port: 443 (default by the type of connection)
• Path: webdav (All lower case)

Possible problems:

Listing directory failed (/): Caused by missing 'webdav' in the More Options section. 

Login error: Incorrect credentials: Username should be the instance 'username' in the user profile.