You are going to get to figure this out yourself, or maybe HP support knows.
I suspect this is down to whatever list of letters HP put after the model number; none, or dw, or dn, or whatever. That’s probably a model with a duplexer, or networking, or wireless, or whatever other letter.
These HP tech specs for this printer omit AirPrint:
https://support.hp.com/lamerica_nsc_carib-enhttps://www.officedepot.com/a/products/5767087/HP-LaserJet-Pro-4001dw-Laser-Monochrome/
These other HP tech specs for the same printer include AirPrint:
https://support.hp.com/rs-en/product/product-specs/hp-laserjet-pro-4001-4004n-dn-dw-d-printer-series/model/35911588?sku=2Z601F
These third-party specs do include AirPrint:
This contradiction leaves you to review your printer purchase, and to resolve this inconsistency locally. Or to return this printer. See if you can find and set up Airprint within the printer. Or call HP support, and ask them to address this.
For the HP documentation for AirPrint on this printer, see page 48:
The link cited there www.hp.com/go/LaserJetMobilePrinting leads the reader on a merry chase, eventually to the less-than-helpful page which itself then links to the Apple page, which doesn’t list this HP printer:
PS: Always get the most current printer firmware loaded!
PPS: Local printer preference is Brother, and preferably a Brother dedicated or multi-function printer with AirPrint, IPP/IPPS support, and TWAIN support for scanning. Which is most of the Brother multi-function printers.