Open Atrium uses an install profile and a drush make based build system. The complete and ready to install, downloads are offered at http://openatrium.com, but it's also possible to build Open Atrium yourself.
Developers, or other users, who wish to build Open Atrium themselves will need to have Drush and Drush make installed. To emulate how drupal.org builds profiles into full Drupal installs you need to use a stub makefile;
core = "6.x" projects = "drupal" projects[openatrium][type] = "profile" projects[openatrium][download][type] = "cvs" projects[openatrium][download][module] = "contributions/profiles/openatrium" projects[openatrium][download][revision] = "HEAD"
Paste this code into a file called
atrium_stub.make and run
drush make atrium_stub.make openatrium. This will assemble a full Open Atrium build into the directory