Google says.....

To get a CAF Number, you can submit Form 2848 or 8821 to the IRS and put “none” in the space asking for a CAF number. Within a few weeks, you will receive an assigned CAF Number from the IRS. Once you have your CAF Number, you should use it on all future forms.Mar 15, 2022

also IRS says......

https://www.irs.gov/businesses/small-businesses-self-employed/what-is-a-caf-number

hope this helped