2 step authentication code

I need to upgrade my Macbook pro software from Yosemite til Catalina. But when i go to App Store and press download, i type my apple-id+password and then get a 6-degit verification code on my Iphone. The problem is that the box, in which I'm supposed to type theese 6 degits, doen't show up on my mac.

my macbook is from 2015, so it should be able to run this software. any suggestions?