Most of the games are forbidden in Germany, so you have to redeem one by one:

One or more games from the Freedom To Buy offer is banned in your country. If you are in one of the countries below, please go here: https://support.gog.com/hc/articles/29306002386845 This article contains codes to redeem the games one at a time, and will allow you to redeem those games which are available in your country