This may be hard to hear for some but it's true. If you ask a girl's number, she may not feel comfortable enough to say no to you on the spot but simply have no interest.

She doesn't owe you a response.

You're making it personal, it isn't. She doesn't know you at all and you don't know her either. Of course it would be great if she could respond something along the lines of "hey sorry but in hindsight I am not interested". But instead she chose to ghost you. In her eyes, you're not worth responding to.

Is someone like that worth worrying about? No. Move on.