How do I convert a pdf file to a word document using Adobe Download Assistant free version?
You don't that is not a function of the Adobe Download Assistant. You would need to use software such as Adobe Acrobat Professional - http://www.adobe.com/products/acrobat.html?promoid=JOLIR to do this type of function.
Moving this discussion to the Creating, Editing & Exporting PDFs forum in case you have specific questions on how to accomplish this task within Acrobat.
Alternatively, you may want to consider the ExportPDF service - http://exportpdf.acrobat.com