You may get this message while installing Trend Micro Antivirus for Mac:
"Trend Micro Antivirus Already Installed. Before installing the software from your service provider, you must remove the version of Trend Micro Antivirus already installed on your Mac."
What Happened?
The installer detected an older Trend Micro program you need to remove to install tha latest version.
How To Fix
Uninstall the older version: