Catching toddler's pee?

I took my toddler to her pediatrician today and she believes what's going on with her is more viral but wants to check for UTI just in case. She gave me a few cups and told me to try and get some urine from my daughter. She is 2. We are just starting the whole potty training.

She did suggest putting her in the bath while standing because that will trigger her to pee and I can put the cup near her to catch it. I have seen her pee so many times like this obviously before I need to get a sample from her....

I tried it tonight but she threw a tantrum because she wanted to play with the cup and hold it. So no luck with her even peeing...

Any suggestions???

Thank you!