Look here look here! The MANDATORY registration for exams closes this Thursday (5/10), so make sure that you are signed up for your exams before then! Or else you will not be allowed to write the exam.
Here is the link so you can do it at once:
https://student.portal.chalmers.se/sv/chalmersstudier/tentamen/Sidor/anmal-dig-till-tentamen.aspx
Best,
snIT