Fire & Flavor All Natural Turkey Perfect Herb Brine Kit, 490ml (470g)

I have one question about the directions for this product, I can't understand why they say to put 2 qts ice in the bag too.

Has anyone used this without using apple cider?

how many pounds will it brine?

I’m running out of time to brine. Will it be worth it to brine for just a couple hours?