There are two ways to perform a Scan Now or Manual Scan: one is using saved settings, the other is after configuring scan settings.
Trend Micro NAS Security™ only performs one Manual Scan or Scheduled Scan at a time, even when you start both scan options at the same time.
Click Scan Now in the Summary screen.
Select Scan Options > Manual Scan from the left menu.
Configure the scan settings as required. See Configuring a Manual Scan.
Click Save.
Click Scan Now to start scanning. The scan progress window appears showing the status of the scan.
Manual scan completion time varies depending on the file size and the number of files to scan. Trend Micro recommends performing a manual scan during off-peak hours.