it says my enrollment appointment is june 19, but i still can't add class right now. Why is that?

You should have been given a specific time on June 19, it's sometime between 8 a.m. and 8 p.m.

I have same issue, I want to take a class, and it's my time to enroll, I enrolled into all courses that I had permission to take, but just 1 course in my program has issue with my enrollment period for no reason.

Must be one of them MOSAIC shenanigans.

Phone up your department this morning when the office opens and they can look into it for you. There's still some bugs in MOSAIC it seems with permissions and timetable conflicts.