Things need to check

• Check you Apache, PHP and Mysql is running.
• Check system variables for mysql, drush and php.

This is the continue series of my previous post Drush. And I assume that your drush is installed and you can see the result in your status as expected.
Here are easy 12 instruction to follow to setup site using Drush in less than 5 min

Radix theme
Radix is the base theme for current Openatrium 2 release. This is a base theme for Panopoly. It has Sass and Compass support, and makes it easy to build responsive themes with Panels. You can follow Radix Handbook for more details.
You can create a subtheme for Openatrium as per your equirement. Just create the subtheme of your mail Radix and you are good to start.
Radix Subtheming Guide

Open Atrium is a collaboration platform designed to help organizations manage their communications, teams, and knowledge.

Project Page - https://drupal.org/project/openatrium
Project Documentation - http://products.phase2technology.com/open-atrium2-documentation

Here is the server requirement for openatrium2 installation

What is Drush?

It is a Command line interface for managing your Drupal website. It can help you install modules, download modules, uninstall modules and much more all without even opening a web browser. It also cuts down on development/upgrade time significantly.