The first thing to do when having troubles with login in SIS (see information about accessing SIS as a student) is to login in CAS. If you have problems with CAS login as well, you need to get a new password for CAS (see information about CAS).
If you are already registered for your study programme, but after login in SIS you see a statement that your login information is correct, but you do not have a role assigned, the most probable reason is that a department of Student Affairs Devision has not yet recorded you as student in SIS. If such situation lasts more than one day, contact your study officer.
The login in CAS, change of password in CAS or login in SIS may not be possible in some browsers in some operation systems (for instance in older versions of Safari in macOS). In case of troubles, update/upgrade your operation system and your browser and use a newly created browser profile. If you still have troubles with the SIS login, but your CAS login is OK, please contact the HelpDesk for SIS.