To use the 12mm LED Pixels with your Adafruit CircuitPython board you'll need to install the Adafruit CircuitPython WS2801 module on your board.
First make sure you are running the latest version of Adafruit CircuitPython for your board.
Next you'll need to install the necessary libraries to use the hardware--carefully follow the steps to find and install these libraries from Adafruit's CircuitPython library bundle. Our CircuitPython starter guide has a great page on how to install the library bundle.
If you choose, you can manually install the libraries individually on your board:
Before continuing make sure your board's lib folder or root filesystem has the adafruit_ws2801.mpy file copied over. You should now be ready to go!
You'll need to install the Adafruit_Blinka library that provides the CircuitPython support in Python. This may also require enabling SPI on your platform and verifying you are running Python 3. Since each platform is a little different, and Linux changes often, please visit the CircuitPython on Linux guide to get your computer ready!
Python Installation of WS2801 Library
Once that's done, from your command line run the following command:
sudo pip3 install adafruit-circuitpython-ws2801
If your default Python is version 3 you may need to run 'pip' instead. Just make sure you aren't trying to use CircuitPython on Python 2.x, it isn't supported!
If that complains about pip3 not being installed, then run this first to install it:
sudo apt-get install python3-pip