I can not open a file. Please help.

I subscribed to Acrobat.com and it still will not work. I am using a MAC OS 10.5.8. I can not upgrade my computer and therefore can not get a new version of Acrobat. That being said I have the same problem on my iPad and updated that Adobe app. The error message I receive is "If this message is not eventually replaced by the proper contents of the document, your PDF view may not be able to display.....