Well, I know it's not exactly a click track, but in the preferences you can set "Metronome while recording" and that will give you a click with whatever instrument you've chosen for your lead-in.

I know it's not exactly what you asked, but off the top of my head, I'd say that would be the easiest way.
I've never used a dedicated click track when recording in BIAB myself.

Usually I pick a drum track (usually MIDI), something that's close to the feel I want.
Then I decide later if I want to keep the simple MIDI beat or find a better sounding RealTrack for drums.

If you right-click on the patch name of the drum track in the mixer, and go to "select custom MIDI style", then hit the "presets" button you will find a list of pretty simple MIDI drum beats based on existing styles.

There are even a couple of straight metronome settings in there, but again I'm not sure if that is what you're looking for either.

Hopefully this helps.

- Jay

MacPro 5,1/12 core@3.46GHz -- OS X 10.15.7 -- ATI 7970 -- 32 Gig RAM -- Crucial 500GB OS SSD -- Samsung EVO 1TB Audio/Sample SSD -- BIAB 2024 -- Logic Pro X -- Cubase Elements 14 -- Too many plugins