If she insisted on paying she was NOT interested in you. You have to look for subtle clues for the coffee girls. Then take a risk.
If she pays-then it means "no f**** way, buddy".
You got it!
You never know good friends can lead to more. Keep hanging out with them something might develop.
Well maybe you just try and find out. Texting is the worst for that! Call them, or meet them again!