Computer Hope is not a great place to find Mac help.
Do any error messages come up while connecting to either computer?
Are the drivers installed on the Mac (or the control program)?
Oh, and PC's are not like Macs. When you connect a device via USB like a disk drive or a flash drive, it does not appear on the desktop. Look under "My Computer", located on either your desktop or start menu. There should be a list of drives. Find your removable drive in that list.