I have read the manual and in the shop.

There is no hint if I have to activate Backbone.

No Steinberg-Key was mentioned.

Windows 10 (64-bit) / Windows 8.1 (64-bit)
Download-Größe: 1,58 GB
macOS Mojave / macOS Catalina
Download-Größe: 1,58 GB
2 GB freier Speicherplatz
Benutzeroberflächen-Sprachen: Englisch
Dokumentations-Sprachen: Englisch, Deutsch, Japanisch

Nothing about challenge - response or USB-key as usual.

You authorize Backbone with Steinberg-Key over internet.
I just bought it.