Successful install but can't open program

Using a MAC to install ADE 3.0.

Successfully downloaded, I clicked on the .dmg file, and it appeared to install correctly.  It left an icon on my desktop called ADE 3.0, a red record-player looking disk.  But when I click on it, it just opens the installer and not the program.  I even dropped it into the Applications folder, but it still just opens the installer.

Also, there was a download of some sort of manual, and when downloaded, it is called welcome.epub.epub.  But my MAC does not recognize .epub and asks what do I want to use to open it.  I had expected it to automatically launch ADE and to display its 'getting started' instructions.

I'm doing all this so I can read an ebook (.pdf format) which I want to download from a publisher who says I need this program to read it.