Good job asking her out! It takes courage, and the more experience you get, the better you'll become at it in the future. How did you ask her out? And what did you respond back?
Not sure if it's the same situation, but when I was in my early 20s, there was this girl in my social circle who was maybe a 6/10. I didn’t really know her well since I was pretty antisocial back then, and she was only a temporary member of the group. One Saturday night, I was hanging out at a friend's house, and he asked if it was okay to bring a female friend over to hang out. I said sure, which was his way of hinting that he wanted me out of there. So, I decided to ask out this girl, the "ugly duckling" of the group. She was kind and said I was sweet, but that she was busy, which was a soft rejection. Later, I found out that another guy in the group was already hitting it.
The point is, Zumba girl might already be getting attention and sex from someone else.