I believe Edamame is a relative of the soybean. It's green, and shaped like a Lima bean. It's also completely safe to eat raw.
A soy bean is tan, and round. Shaped very much like a garbonzo bean. I believe it's protein content is higher and it does have significant digestive issues if consumed raw. That's why it's roasted before being added to animal feed.
My thought is Edamame would be a fine, but expensive snack for your chickens. Personally I would eat the Edamame myself and toss the chickens a handful of cat kibbles or leftovers from meals that you don't want to eat anymore.