Here is Google's link to OEM (Original Equipment Manufacturer) Drivers. In that case, you'll have to get the driver from the manufacturer, and install it on your PC yourself. You might be lucky enough that these work for your device - but probably not. The App Inventor setup software comes with drivers for a very small number of Android devices.
Unfortunately, different devices require different drivers, and Google and Microsoft have generally left it to the device manufacturers to develop and distribute the drivers. The driver is a software module that lets the PC interface to the device hardware. In order to connect your device to a Windows PC over the USB cable, you need to install a driver on your PC.
This page contains help for when you have connected your Android device to a Windows PC with the USB cable, and the Connection Test says that the device is not detected.
