Here is a response from Tech Support. My bad! Has anyone been using it ?

Hello Dr. Robert Prince-Wright, Thank you for contacting Wolfram Technical Support regarding issues loading HadoopLink. Have you installed HadoopLink from the GitHub repository as well as its dependencies? According to the blog post (https://blog.wolfram.com/2013/07/31/mathematica-gets-bigdata-with-hadooplink/), you will need the following to run HadoopLink:

1. HadoopLink folder from: https://github.com/shadanan/HadoopLink
2. Apache Ant
3. Mathematica (version 7 or higher)
4. Wolfram Workbench (for building the documentation notebooks)
5. Hadoop version 0.20, patched to include the typed bytes binary data support for Hadoop Streaming.

Please let me know if you come across any issues installing HadoopLink and those dependencies.