Audio Interface. If your computer has a Line-Input, try connecting the Line-Out of the AC-3 to your line-input. (NOT YOUR MIC INPUT)

If you're trying to do acoustic tracks, all I can say is that you might be disappointed.
I tried what I assume you're trying to do, get acoustic tracks from an AC-3 pedal, and it sounds poor. I thought it would be a cheap alternative from miccing a real acoustic, but trust me, the AC-3 is garbage.

The only thing it's good for is if you're desperate to get an acoustic sound out of your electric in a live situation. That's it's main purpose, not to get an actual Acoustic sound.

A magnetic pickup on a guitar cuts a LOT of frequencies out from your guitar's strings that are present on an acoustic guitar's tonality.
You cannot EQ frequencies in that are nonexistent because of the magnetic pickup deleting them.

If you really want to go through with this, you can, but I'm just giving my two cents of when I did what you are doing. If you really want an acoustic sound out of a line, you need piezo pickups. I'm sure there's some cheap electric-acoustic guitars out there that'll sound 100 times better than that pedal.