usually

"hey good meeting you lets hang soon"

then they say "great meeting you too and yes lets hang soon"

"hey good meeting you lets hang soon"

To me personally, that sounds like you are blowing them off.
Even if not it could come from any of the AFCs messaging her.

Get a bit more jokey and flirty, and avoid all the nicety bull.

Firstly you want to spark an emotion.
Secondly, you need to create a connection with her.
Then lastly, set up the next date.

The easiest emotion to spark is usually laughter. Using something funny from your first meeting not only makes her laugh but also creates a connection, something she can relate to, giving her the impression you are already fairly familiar. Then throw in a nicety.

Say she said she was a coffee addict.
send her "just had a coffee made by the hand of god. so amazing i just had to tell you. hope your day is good too. (name) "

depending on how she replies changes how you proceed

What you do and say before you get her number matters a LOT!

First of all, if you ONLY get phone numbers from women you are GENUINELY attracted to, your success rate will skyrocket. Don't treat it like a sport where you just get phone numbers just for the sake of boosting your ego.

Second, time bridging is also important. Have a more solid reason to get her phone number. A solid plan. For example, if you talked about a certain bar or restaurant during the conversation, get her number while saying that you would like to take her there next Saturday.