LedControl is an Arduino and ESP8266 library for MAX7219 and MAX7221 Led display drivers. The code also works with the Teensy (3.1)
The only difference from origin is making it compatible the non avr chips like ESP8266. U
Documentation for the library is on the Github Project Pages
Just download this repo (don't need to clone it!) by clicking on "Clone or Download" button and then Download Zip. Or just follow this URL: https://github.com/9khil/LedControl/archive/master.zip
Unpack the zip you downloaded and copy that (LedControl-master) to Arduino Library folder.
If you cloned the repo, just copy LedControl to Arduino Library folder.
Mac OS: ~/Documents/Arduino/libraries/ Windows: My Documents\Arduino\libraries\ (I guess)