Adding atlas to resourcepack/ implementing in datapack

I am stuck after reading the atlas wiki. I have attached a datapack and resourcepack. Both made to work together for 1.21.3, I need help updating them to 1.21.5. I can't wrap my head around implementing atlases.
Could someone help me do one or two of the textures and implementing them into the datapack, I hope I can learn how to do it so I can do the rest myself.
Cheers
here follows what the datapack is supposed to do:
Crafting an item - which is textured with a custom texture that is playable in a jukebox.