Download and install Putty from here: http://www.putty.org/

From the list of downloads select the binary called just putty.exe from the section For Windows on Intel x86. This will prompt you to save the file. Save it onto the Desktop for now.

Install Drivers

Next, install the latest drivers for the cable chipset.

There's two possible chipsets. The older cables use Prolific brand, the newer cables (as of 2017) use SiLabs brand. If you're not sure which you have, just install both drivers! There's no risk and the cable will work no matter what

Prolific Chipset

For the "Prolific Chipset"  cable, grab the drivers from here

This will save a zip file called PL2303_Prolific_DriverInstaller_v1_7_0.zip (or similar). Unzip this onto the desktop and within the folder run the installer called PL2303_Prolific_DriverInstaller_v1.7.0.exe

If you're having issues, you can also try this older PL2303 driver (v1.0.13)

SiLabs Chipset

For the "SiLabs Chipset"  cable, grab the drivers from here

This will save a zip file called CP210x_Windows_Drivers.zip (or similar). Unzip this onto the desktop and within the folder run the installer called CP210xVCPInstaller_x64.exe
(or CP210xVCPInstaller_x86.exe if the x64.exe doesn't run)

Complete Installation

Click through the entire driver installation process to completion

You may need to reboot!

The driver is installed in such a way that when you later plug in the USB console lead, it will still launch the “Found New Hardware” wizard. If you allow the Wizard to search the Internet and install it should work.

When it has finished installing the driver, you should get this message: