I haven't expected that somebody would want to use them as gifs, so my suggestion is to use a web png to gif converter.
In the description it says that each is X amount of frames, that means that you have to crop the image into X amount of equal sized parts in order to get the animation. (For example idle is 8 frames that means that you need to crop the image into 8 200x200 images). I suppose you're going to use the asset in a game, so you can crop the images inside the game engine (if you don't know how look somewhere on how to do it for the specific engine that you're using).