how do I add a printer?

Hi,

The Brother HL-L2370DW is listed in About AirPrint - Apple Support as a model supporting Apple's AirPrint technology. This means that the printer will work with macOS 12 Monterey without additional drivers, provided that the printer and the Mac computer are connected to the same network (Wi-Fi router).

For a wireless printer connection to your Wi-Fi router, the easiest way is often a manual setup. As John Galt also indicated, a setup disc is rarely of any use. If your router supports it, WPS (Wi-Fi Protected Setup) may simplify things. See: https://download.brother.com/welcome/doc100810/cv_hll2310d_use_oug_d.pdf#GUID-C0BA1488-7D43-46F9-8A70-16207BE4DB49 .

Brother specifically recommends using AirPrint.

https://support.brother.com/g/b/downloadlist.aspx?c=us&lang=en&prod=hll2370dw_us&os=10072

You may want to check that the latest printer firmware is installed.

AirPrint works with wireless (Wi-Fi) or wired (Ethernet) network connections, so you could choose to wire the printer by Ethernet cable to one of the LAN ports of the router (instead of a wireless printer connection). Ethernet may be more stable.

A MacBook Air would normally be wirelessly connected to the router.

AirPrint would allow you to print from an iPhone or iPad as well.

Use AirPrint to print from your iPhone or iPad - Apple Support

Throw it away and read Add a printer to your printer list so you can use it on Mac - Apple Support.