Thank you Megangeckler. The difficulty you are currently facing with the Adobe Download Assistant can be solved by removing the currently installed Adobe Download Assistant from your applications folder. You can find more details under the Known issues section of Troubleshoot Adobe Download Assistant - http://helpx.adobe.com/creative-suite/kb/troubleshoot-download-assista nt.html#main_Known_issues.
Prior to installing CS6 I would recommend running any available uninstallers located in the Applicatons/Utilities/Adobe Installers for CS6. If you are very lucky this should clear up any additional installation issues you may face.
If you do face any additional difficulties with installing CS6, not the Adobe Download Assistant as referenced in your screenshot, then please remove any remaining Adobe Creative software and follow this by running the CS Cleaner tool. You can find details on how to download and use the CS Cleaner Tool at CS Cleaner Tool for installation problems | CCM, CS6, CS5.5, CS5, CS4, CS3 - http://helpx.adobe.com/creative-suite/kb/cs5-cleaner-tool-installation -problems.html.