According to the german press release at https://news.rub.de/presseinformationen/wissenschaft/2021-06... a preprint of this paper will be freely available online.

Edit: English articles are now available at

https://www.wral.com/security-flaw-found-in-2g-mobile-data-e...

and

https://telecomtalk.info/2g-mobile-standard-isnt-safe-cybers...