I NEED HELP!!

So I went in to see the status of my FAFSA and saw there was a missing document and was told to request the 2023 IRS tax transcript and I’m doing so online but it is asking me for a customer file number?? Does anyone know where I can find this number!! I’m first gen and my mom wouldn’t know half as much as I do because a very sweet lady helps her do all her taxes. Please let me know if you know where I can find this number!!!! I’m hoping to submit it asap because I’m scared ima have to pay my classes before I get a return Thank you so much:’)