I set up the kit , But killing zombies doesn't drop the kit , I set up AK and found that zombies carry AK, but kill zombies and AK is gone. There are no other items

I killed the zombie, and the zombie didn't drop the kit I set

By default zombies won't drop their kit (this plugin is only intended to put clothes/attire on them and define melee weapons). If you want them to drop their kit (clothes/belt items etc) then you'll need to combine it with somehting like botspawn