How to read and convert a acsm file to a pdf file?

A .acsm file is just a token for the purchace/loan of a book, which will come in a real DRM file, either .pdf or .epub (it's choice, not yours)

The .pdf or .epub will be limited to reading on ADE or other compatible Adobe DRM software or hardware readers;

and these must be authorized by the same ID as the one used when the book was first accessed.

To open the .acsm file in ADE and get ADE to convert it to .epub, .pdf, either:

• drag/drop it onto ADE from Windows Explorer
• open it by making sure .acsm files are associated with ADE, and double clicking in Window Explorer or opening from your browser.
  A bug in Windows 8 sometimes makes it very awkward to make that file association.  Post back if that is your issue.