The SkyPack is a texture pack for the Hypixel MiniGame. There are custom texture, it means that YOU MUST USE OPTIFINE. There is no more to do, you just install the texture pack and the textures will automatically change. Even the custom weapons / bows like the Runaan's Bow or the Pigman Sword will be change (if you don't know how to install a texture pack, you can check how on this video: How to install a Texture Pack )