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

There should be 8 sub-directories:

aluminum_brushed
brass_brushed
bronze_brushed
copper_brushed
gold_brushed
silver_brushed
steel_brushed

There are 6 main brush types and all of them has many variations. There is no need to download whole set if you only need part of it, just download the zip file and corresponding blend file and you're ready to go.

The whole set is almost 50 GB ! when uncompressed.

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