Uploading Draftsight 2015 to MacBook Pro - why is it not working as this is my 4th renewal?

Latest version of Draftsight not working on my Macbook Pro.  I have used and renewed Draftsight over the last 2 years, but the latest version not able to be installed.  Error saying I need to install available updates for the application and Mac OS X. I have done this, but still getting same message.  My MacBook Pro is 10.6.8. Any assistance would be appreciated.