The rules general rules for conditional admittance are stated at the Stockholm university webpage.

It is also good to be aware that you can only be accepted to a maximum of 45 ECTS credits, and if you get conditionally accepted to a course this will also count as part of those maximum 45 ECTS credits.

So if you get conditionally accepted to a course of 30 ECTS credits, all courses you have put on lower priority that are bigger than 15 ECTS credits will be removed from your application.

If you cannot show eligibilty to a course to which you are conditionally accepted, you cannot be registered to the course.