Download all files in your desired directory and unzip them all.

There should be 8 sub-directories:

aluminum_flat
brass_flat
bronze_flat
copper_flat
copper_flat_2
gold_flat
silver_flat
steel_flat

and 9 files:

aluminum_flat.blend
blender_assets.cats.txt
brass_flat.blend
bronze_flat.blend
copper2_flat.blend
copper_flat.blend
gold_flat.blend
silver_flat.blend
steel_flat.blend

You can of course copy and use files as you please.