Resolution:
When launching TIBCO ActiveMatrix Adapter for Files (Unix/Win) (FA) 6.0.0 installation package, it may prompt to install TIBCO Adapter SDK (SDK) 5.6.1. If you have already installed SDK 5.6.1 as a separate product or with some adapter installation, then the installation will prompt you to confirm on reinstalling SDK 5.6.1.

You can check your environment to verify if there is already an SDK installed first if you are attempting a silent installation. Look for <TIBCO-HOME>/adapter/ sdk/<SDK-Version> or <TIBCO-HOME>/sdk/<SDK-Version> folders and explicitly verify the SDK installation. A better way may be to launch the TIBCO InstallationManager GUI Utility which lists all products installated along with a dependancy list.