With Fragen-Lern-CD version 6.0 and up you will find a registration code on the left inside of your CD case. You can use this code to register with FahrAPP.
Download FahrAPP on your smartphone
or another FahrAPP version from https://www.fahr.app
. Open the app, click on "Register" and enter the registration code from the inside of your CD case (you do not need to provide a driving school code / Fahrschulcode).