I have the Zoom G2.1u, and I have no idea how similar our pedals are or not.
Anyway, my Zoom pedal only has a completely clean AC30 amp model, so that's not much of a help. If yours has an AC30 amp model, play around with that and see if you can at least get some crunch out of it. That's where I would start. Then the delay is the next obvious thing. A delay time of about 430 milliseconds will get you in the ballpark for a some classic U2 delay times. Make sure it has more than just one or two delay returns. Throw on some reverb and play with the pickup selector on your guitar and you'll at least start to hear some familiar sounds. Using those Herdim picks also helps add a bit more Edge sound if that's what you're going for.