There are courses where you can get your grades via Campus Management, and there are courses where your examiner has to transfer your grade to the International Office at the Law Department via e-mail.

You will find that information for each course in the course descriptions that are available on the website
http://www.jura.fu-berlin.de/en/international/studierendenaustausch/incomings/kurse/index.html (at the bottom of each course description).

Please check your Campus Management account regularly.