Fixed it. Turned spotlight indexing back on and it installed without a problem.
Thank you for your post.
The updater is using the index on your hard disk to locate the previous version of FileMaker Pro. To reindex your hard disk, go into System Preferences, click the Spotlight icon, click the Privacy tab, and drag the Hard Disk into the large list. If prompted for confirmation, click OK. Remove your hard disk from the list and close System Preferences. Spotlight will reindex the contents of the hard drive. When finished, run the updater again.