I'll need to get the installer log files to troubleshoot the error. Please review the FAQ Where do I find the Flash Player installation log on the Macintosh? and provide all 4 log files listed (Adobe_ADM.log, Adobe_GDE.log, install.log, and FlashPlayerInstallManager.log). Please read through the FAQ first, then run the installer again to get the logs for the same installattion attempt (this is required). After gathering the log files, upload them to cloud.acrobat.com/send using the instructions at How to share a document and post the link to the uploaded files in your reply.