Don't know any Arduino libraries that would support USB devices directly connected, anyway you can't plug in a USB A port into an Arduino.
USB is a Protocol so devices need to tell a host....I'm a usb joystick.....host sends back....tell me what you need.....joy send data from pots and digital switches...etc
If you read though the description of that link I gave you, it's mentions
The USB Host Board is based around the Microchip 24FJ64GB002 microcontroller which contains a built-in full-speed USB host controller. This allows the board to interface with and control any USB slave device - flash drives, keyboards, digital cameras, bluetooth dongles, and much more!
The USB Host board is designed to be as simple to use as possible. All of the complex USB programming is contained in the microchip so there is NO USB coding required in your application. This saves valuable programming space and saves you from having to code and debug USB interface routines. The onboard microcontroller has a bootloader and is easily updatable with any of our free USB Host driver software.
So all the USB communication from device to this chip as detailed above is done for you. All you need to do is plug in the USB and connect I2C or RX/TX and +5V from the arduino and then pull data from the registers within the chip. The description is quite detailed in how to use this device, which will contain the data required.