Guide to access the interactive versions of the said textbooks. The license should hold 3 years after access.
The general idea is as follows:
가) Register on their website using the code in your book and an e-mail-address you can access immediately
(add more access-codes if you like)
나) download the hueber-app and unpack it somewhere where you can spare some 1 to 2 GB of Data
다) start the app, log in
라) download the books that you saw in your “book shelf“ on the website
DO NOT LOCK OUT. Just exit the app once you are done learning and restart for a new session.
Beware that the in-app writing and erasing is very bothersome, but the plenty tasks and audios might help you.