A Windows program that you write yourself does not talk directly to your HID device, but instead must work through a sequence of rather obscure and confusing Windows API calls. These API calls ultimately communicate with the HID and USB device drivers that are built into the operating system.

These API calls are very low level, often requiring that you first set up complicated data structures and fill in these, in just the right way, before you can call the API function.

Working with this very old-fashioned API approach is time consuming and error prone, and requires deep knowledge of the PC operating system. (For most people, that's Microsoft Windows.)