1. Extract zip file to the desired folder.
2. Open blender.
3. Go to File -> Link or Append (whatever suits you better).
4. Browse to where you extracted the blend files and select either one (center_origin is more convenient).
5. Within the blend file select the object folder and switch to Thumbnail Preview to see image previews for all the models.
6. Select the one that suits you and press Link/Append from Library.
7. Happy Blending!