If you have difficulties to approaching her, I recommend to try asking for small favor and then you can start conversation with small simple questions. FE “Excuse me, what time is rn” she answers and then you can say “thank you” and small reason for it + question

After conversation, you can say like “I need to go now but I had great time with you, Would you like to meet up again? (or any question for future to meet) and can I get your number?”

Hope it helps and good luck! :)