Hello,
the QR code can be found by clicking on the "Devices" ("Geräte") button at the top. It allows you to connect the Android version to the desktop version but only for these purposes:
1. When clicking on a phone number in the desktop version the phone number is sent to the Android phone and can be called.
2. When clicking on a location the location is sent to the Android phone and you can navigate to it.
Please don't hesitate to contact me again if you have further questions!
Kind regards
Dominique Gunia