Ok since this is Acrobat on Mac OS you will not be able to simply install the trial. Instead lets first try rebooting in safe boot and logged in as a Root user and try installing again. Please feel free to respond if you need additional details on how to complete either of these actions and I will locate the appropriate Apple technical document.
Ok and you did log in as root and saw Welcome to Mac OS X Safe boot?
If so we will try the longer solution which seems to have lead to success for many users. Please complete the following steps:
- Remove all Adobe Creative Applications using the uninstallers located in Applications/Utilities/Adobe Installers
- Run the clean up utility directions can be found 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
- Reboot in Safe Boot in the Root User account
- Download the Adobe Application Manager from https://creative.adobe.com/
- Download and install any Adobe Creative application besides Acrobat
- Download and install Adobe Acrobat
- Open the Adobe Creative application download previously
- Open Adobe Acrobat
Please feel free to respond to this thread if you have any questions about any of these steps. I would recommend completing them in full as several users have reported success by following these directions.