So, anytime you meet a girl at her place of work, she has to be kind to you. Good customer service means, good eye contact, bubbly personality, engaging conversation, etc. If she does not routinely do those things, she will not have that job. Therefore, It can be hard to know if a girl is actually into you, when you flirt with her at work.
Also, no girl is ever going to text you. It's an unwritten law somewhere. If you give out your number to 100+ girls, maybe 1 or 2 will actually text you back. Girls do not take the lead. If you are interested in this girl, tell you think that she is cute, and that you would like to buy her dinner, or coffee or something. Ask for her number. If she doesn't give you her number, then say no hard feelings. That's ok.
If she does give you her number, invite her out at most three times. If she does go out with you 2+ times. Then keep taking her out. If she does not go out with you. Then again, tell her no hard feelings. At that point, it's time to find someone who is interested in dating you.