I have drupal core installed on my web host server and would like to install a panopoly distribution to it now. I have uploaded and extracted the tar.gz file to my docroot and can't seem to figure out how to install panopoly now. What should my next steps be? How do I install the install.php from panapoly? When I run the www.domain.com/install.php I get the message, "Drupal has already been installed"
If your website is not configured and you just has installed a pure drupal core without any modification , then you can forget about it and install a panopoly distribution instead, I mean you don't need a drupal installed before installing that distribution. Installation is pretty easy and straight forward in this case, you can read about it here.
In the other case if you have a website installed and running using drupal and you want to add panopoly to it , then the module itself has provided a documentation about how to get it done. just follow the steps.