This uses ItemsAdder or Oraxen plugins to apply custom textures to AdvancedPets menus. This is as simple as just installing one of those plugins, adding this pack and custom AdvancedPets configuration - that's it!
Complete guide on how to install with those plugins (or just as a resource pack) is included within the pack files.
Full installation support is available for customers of this pack on our official AdvancedPlugins discord server, any questions or problems will be answered there.