How do I find my WPA2 Personal Key/Password
How to get My older HP wireless printer/scanner to be recognized by my new iMac desktop
iMac 21.5″, macOS 10.13
Hi,
It would help to know the exact HP printer model.
The normal connection method would be via a Wi-Fi router (that is, one should avoid a direct Wi-Fi connection). You will have to check the wireless security options offered by the router. If in doubt, please post back with the router make and model (do not post any serial numbers or access codes).
The following article could perhaps be of interest to you.
Recommended settings for Wi-Fi routers and access points - Apple Support