To run the Creately Desktop you’ll need a copy of Adobe Air installed on your computer. When downloading Creately Desktop, you will get an automated request to download Adobe Air as well. When you click the download button, it will automatically be installed first, followed by Creately Desktop.
If you already have Adobe Air you can make sure you have a the required version before installing Creately Desktop. Creately Desktop requires Adobe Air version 2.5.x or higher to work correctly. The requirement is the same on Windows, Mac OS and Linux. You can check which version you have installed by following the instructions here: http://helpx.adobe.com/air/kb/determine-version-air-runtime.html
Whichever version you have we recommend you run the latest version to ensure you have the latest features, improved performance and security fixes. You can download the latest Adobe Air installation here: http://get.adobe.com/air/
For Linux specific discussion refer to this article.