That strikes me as terrible advice. No such thing as too pushy?! There’s clearly a difference between being engaging and being uncomfortably assertive, to the point of being an arsehole. Pushy behavior will dissuade more people than it’ll attract, and encourages a retaliatory response. It’s unwelcome confrontation rather than unwelcome persistence.
Immediately trying to obtain a phone number and ignoring all other members of a social group isn’t a magic system for endearing yourself towards anyone. Save yourself the $99. Just act using a degree of common sense, and with any available charm.
To the op: you’re just going to have to find some way to open that door. Go out and get on her floor. I think you’ll soon see that following this advice will result in everybody wanting you
Reading the OP it seems clear she wasn’t interested in your friend from the first meeting where she disappeared after a few min. If she had been keen, she would have either stuck around, or given a signal that she was reluctant to go (e.g. friends wanting to go to another bar etc). Let this drop would be my advice - although I guess you’ve worked that out from the other responses by now!