They are only referring to the front panel USB connectors that are included in the case. The motherboard will still have all its own ports coming out of the rear I/O.
What do you want to do?
Getting a part that will fit your exact case is going to be tricky, but they should be out there, most use fairly standard spacing on the USB ports, but they usually bundle audio and sometimes SD card slots on front panel headers.
If you need more ports you can buy a standalone PCI expansion bracket with USB 3.0 or anything else you want.