I am leaving this comment here for those who have built a magic mirror using raspberry pi zero hoping that it will help someone.
After trying to get the sensor (DHT22) to work with various modules I confirm that I managed to make it run with this module. The only difference was that in step 3 of the instructions I installed wiringPi library as described in here: http://wiringpi.com/download-and-install/ , which is simple a sudo apt-get install wiringpi command in the main directory of the project ( /MagicMirror ). Other than that, just make sure to enter the correct GPIO pin in the config.js file and you are ready to get some measurements.
Two words only… Thank you!