To share files / folders on Mac, please logon www.drivehq.com, go to Online Storage & Sharing, then select a folder and click on the "Share" button in the tool bar. Once a folder is shared, it is accessible from a web browser or any FTP client software. (Look in the special folder \DriveHQ Share\, which contains folders shared to you from other users.)
Please note you cannot share a folder using regular FTP client software; you can do so from a web browser or DriveHQ FileManager client software. (Sorry, FileManager is not available on Mac)