Cubase on a Mac, is an interface essential to record guitar?

Hi, I have now got a Mac and am trying to run Cubase AI7. Must I have an interface to record guitar?
It didn’t need one on Windows. Garage band works fine on this Mac with either my Behringer mixer or a Zoom 505-II effects pedal. But Cubase does no seem to recognise any guitar signal.

My Mac is a Retina 4K using Catalina. Cubase is fully updated.

Hi,

Make sure Cubase has enabled Mic in the System Preferences, please.
Open macOS System Preferences > Security & Privacy > Privacy > Microphone. Enable Cubase here.