Blightfall

I'm trying to play Blightfall with my friend, but we are having an issue with the world, if we create a new world it is an ordinary world.
I tried uploading a world that i generate on singleplayer, but when it is done uploading i get a pop up in the lower left corner of my screen "Fatal error occured (cannot unpack archive)"

My world is 161 mb, but the modpack is supposed to have a premade place, if i generate the world from the server page, it will be a normal world without it and i don't know how to shrink the size of the world

Could I use mcedit or do you happen to know any other tool?