So Did I do something wrong..? Did I wait too long to get her number? Was she just not interested?

For context I’m 32 and never had a gf or a relationship before. I was part of a very conservative culture where dating wasn’t allowed, but I e become more independent recently and trying to date now
I want to tell you about a situation I had. I feel like I learned from it and hopefully by the time you respond to this I will have had 1 or even multiple dates.
So I went to this meetup for 'single professionals' and I had a conversation with this lady. I think we might have spoken for about 7-10 minutes and she did seem interested in the conversation and was laughing at times. But unfortunately and unideally, someone else joined the conversation too. That obviously wasn't ideal, but I tried to not let it affect me and not impact anything. I was polite and tried to talk to him as well, but i noticed that she was asking him questions as well.
Idk why he was staying there as he said 'hey i'm just eves dropping' when he came to our area where it was just me and her talking. I think he was there for like the same amount of time that me and her were talking ant he was talking to her as well and then she eventually left. I was there standing with him and trying not to act affected and keep my cool. I was waiting for her to come back but then she said 'hey nice to meet you i'm going to go.'
I was going to ask for her number when she came back but she just said she was going.... I didn't want to ask for her number right away, i wanted to talk a little more and establish rapport because we never met before. ....
I don't know what happened. I mean did I wait too long to ask for her number, should I have not waited more than 4-5 minutes before asking for her number, so that it would have been before this other guy came to talk and 'enter' our conversation? Did she just not have enough interest, because she should have came back to talk to me when she returned or what? I think i was interesting in our conversation and she kept looking at me when this other guy came in, but i didn't want to appear rude or antisocial but telling the other dude that me and her were talking to each other.
So I guess I’m asking is did I take too long to get her number? People tell me the other guy shouldn’t mattered and I agree. Or was she just not j tweezers to begin with because she would have came back and spoken ti me more and given me another chance to get her number. Okay thanks bye.