To install Achievo, you need a webserver with PHP5 support, and a database server (MySQL5+ is fully supported if it's not running in strict mode, PostgreSQL and Oracle support is present but may not be fully functional). Unzip the Achievo archive somewhere in your webservers' documentroot, and read the installation instructions (in the doc/INSTALL file after you unzipped Achievo, or online.
When upgrading from a previous version of Achievo, no database patch is necessary. If you use the docmanager for uploading files check the configs/docmanager.inc.php if all upload extensions are available for you.
Last month we received an email from a security company that they discoverd 2 Vulnerabilities in Achievo. This security bugfix release will fix both issues. Here is the complete list of changes: