Before the course starts

Limited numer of places

This course can only accept a limited number of students due to hardware and space limitations It is very clearly written in the course information
http://www.kth.se/student/kurser/kurs/DD2425?l=en_UK
that there is a limitation but unfortunately people do not seem to care about this and it creates huge problems. You have to apply for the course on time and you will be admitted in competition with other students. 

There does not seem to be any way to stop people from signing up despite the limited number of places but if your coordinator or you yourself add you to the course without getting an approval from the person responsible from the course you will most likely not be able to take the course.