All this datapack does is update the iron_nugget_from_blasting.json and gold_nugget_from_blasting.json smelting recipe to return an iron and gold ingot, instead of an iron and gold nugget. For balance, armor and tools must be smelted in blast furnaces, and it will take 200 ticks (same amount of time as a standard furnace), instead of the default 100.
Install this the same way you'd install any datapack. See here: https://minecraft.fandom.com/wiki/Tutorials/Installing_a_data_pack