Unfortunately, there are currently issues with the “JGU-Ausweise-App,” especially on iPhones. Our data center (ZDV) is working on a solution. In the meantime, please use this link or one of the QR codes on our self-service terminals to access your library card:
https://account.uni-mainz.de/id-cards
If you have any questions, feel free to contact our library staff at the information desks.