To be able to live in SSSB's housing, you need to study and complete at least half speed at an SSCO-affiliated university each semester, and be a member of the university's student union. Exact terms and rules can be found here (https://sssb.se/soka-bostad/hur-soker-jag-bostad/koregler/)
In cases where your queue time has not been registered with SSSB, you should contact your student union.
You can collect up to 90 queue days at SSSB without being a member of a student union, then you need to become a union member to be able to continue collecting more queue days.