Just go to meet.physik.fu-berlin.de and log in. You can find our documentation here.

The login at meet.physik.fu-berlin.de is simply your ZEDAT username and password, but a Physics account is a requirement. If you don't have one, write an email to zedv@physik.fu-berlin.de with either your collaborator or the lecturer of the course, for which you need access, in the CC.