Where to find study room or similar?

Does anybody know if there's anywhere you can book/rent a study room in Heidelberg? I'm an exchange student and unfortunately have no WiFi and can't get reliable phone coverage in my room but need to do a video call. Might there be anything at the public libraries or somewhere that you can book (or first come first served) a cubicle/room that's quiet and has a wifi connection? I originally thought maybe I could do it at the uni library but unfortunately they require at least 2 people.