Hi, Bernd.
I think all Gluu CE repos require you to have a paid support subscription. You are supplied with set of credentials to access them as a customer. The change was introduced more than a year ago, actually. From that time on, Janssen has become Gluu CE's substitution as a free-to-use community solution, and Gluu CE is considered a legacy branch now. You can learn more about it here: https://docs.jans.io/v1.1.5/