If you are using Java Edition, you do not usually need to rename the file. Instead, you move the .zip directly into the game's internal folders.
In Minecraft , "mc.zip" typically refers to world, skin, or resource pack files that have been compressed into a standard ZIP archive but need to be converted to specific Minecraft file formats (like .mcworld or .mcpack ) to be automatically imported by the game.
Rename filename.zip to filename.mcpack . Step-by-Step Conversion (Windows)