Heyyy, Joffer took the plunge - time to change your signature!
If the Astaro sees a USB memory stick, it assumes there's an unencrypted backup on it, and attempts to restore a configuration from it. If it sees a CDROM, it assumes that it's supposed to install from scratch; the Astaro Smart Installer USB stick has firmware that emulates a CDROM.
Cheers - Bob
I closed this one because we already provide such an USB-Stick installation method.
In addition to what Bob said: We don't build and provide .ISO files for it every week though, mostly because of "lack of interest" from the outside world (but also, to a lesser degree, for disk space reason).
If you have one the USB Sticks and really need that ISO, contact flichtenheld via PM.