This asset requires a copy of Asprite, you can find it here www.aseprite.org
Aseprite importer helps you integrate your animations to Unity. It takes the .ase file and will create a texture with the spritesheet, the json atlas, the sprites separation in the texture, the AnimationClips and a prefab with all the animations on an Animator. It will also separate your tags into different animations if you want.
Animations are auto-imported when changes are made to the .ase file, and it can all be configured in the file's inspector.