Everyone has to start somewhere. Good for you!
Pure street game like this is very difficult. You've started with one of the more difficult non-bar venues. I wouldn't recommend.
You are trying game on hard mode before having the skill set to do game on hard mode.
In 2012, Roosh called street approaching the most difficult approach venue.
I'm not sure where you are geographically located. It doesn't sound like you live in the United States. In the USA, New York City is one of the few cities where street game is possible. In most larger USA cities, street game isn't very viable. Most US cities will have better outdoor game options on paths/in parks. Indoor game in retail venues is an even better option.
This isn't that good of an opener. She's clearly waiting for a taxi or rideshare app. You won't have much time.
You need to go very direct in this situation.
@We_ArE_VeNOM is very good at direct game on this forum.
You needed to open with "I like how you look. I want to get to know you better. Would you like to get together for drinks soon?"
There's no question about intent there. You have declared your interest and set the frame as a man to woman, sexually oriented interaction. She'll be impressed with your boldness.
If she's interested, it will be mainly on your looks. So make sure that you look your best when doing approaches and you have a lifestyle centered around looking good. Exercise regularly and eat right.
If she's not interested, she will either respond "I have a boyfriend/husband" or she'll be cordial, compliment the fact you were bold, and then say she's not interested due to her boyfriend or husband. The ruder females (most females) will use the first statement.
Your frame stinks. You need to frame every interaction as if you are communicating in a man-to-woman, sexually oriented frame.
In a different setting, where you could have had a longer interaction, you still needed a better, more specific opener. You didn't give her much to work with initially, even if she were interested (she likely wasn't).
She likely gave you a bitchy attitude because she's an unpleasant person in general and already has a boyfriend or husband. In non-bar approaching, many of the women you'll approach will already have a boyfriend (and if you aren't careful on venue selection or looking for wedding rings, they might even have a husband). The problem is that approached women with boyfriends rarely disclose their boyfriends. They act standoffish and the conversation fizzles out from never having found any momentum to build on. The man wonders at the end of the interaction whether she was unattached and seeking new penis or was not in the market for new penis.
When I consider the interaction as a whole, I think you were approaching a woman with a boyfriend who wasn't interested in new penis in general. Women with boyfriends can be interested in men, but only if you are superior and she's not happy in her current relationship.