There are two steps needed to get started with the tower light: installing the USB serial driver, and plugging in the light.
Inside the tower light is a microcontroller connected over a CH43x USB-to-UART chip. To access the tower light over USB serial, you will need to install the CH43x driver.
The driver is available for Mac and Windows. It is already built into Linux.
Download the driver below for your operating system and install it. If you would like more detail, check out the guide on installing this driver.