He un-checked the box. Never trust 'recommended'.

: Always plug the microscope into the USB port before opening the software to ensure the device is recognized as an active camera source.

If you are using a modern operating system, you likely already have the software needed for a basic preview:

I can provide the or a step-by-step setup guide once I know your specs!

: Apps like Cheese or GTK+ UVC Viewer are commonly used. Recommended Free Software Downloads