I applied to a course through Preference Selection, but I was not admitted. Is there still a chance to enroll?

Yes. It is not unusual for a student admitted to a course through Preference Selection to drop it, thereby creating space for other students. If the course requires instructor permission to enroll, you may request permission through YCS while the registration system is open. If the course does not require permission and the course has open seats, you may add it to your registration worksheet while the registration system is open.