Unpack the ZIP file somewhere on your computer.

For the older version (Blender 2.79-3.6) a "Scenes" and a "Texures" folder will be generated. After that you can open the .blend in the "Scenes" folder or use the "Append" feature in Blender to add the model to your scene.

For the newer version (Blender 4.0+) no folders will be created, because the textures are packed in the .blend, but you can unpack them in Blender if you like. Just go to "File -> External Data -> Unpack Resources".

In Blender versions 4.0 and later, the Principled BSDF shader got some changes and now handles specularity a bit different. Therefore I tweaked the settings of some materials to take those changes into account.