In order to add a new sensor, click on the Add Sensor button in the sensor list’s toolbar or select Add New Sensor from the Edit menu.
This will launch the Add Sensor Wizard.

Click Next to proceed to the selection of the data acquisition.

Please select NetFlow Collector. This will lead to the NetFlow Collector selection screen:

From the list, check the device(s) you would like to monitor. Then click the Next button. This will open the Filter window:
PRTG Traffic Grapher is an easy to use Windows software for monitoring and classifying bandwidth usage. It provides system administrators with live readings and long-term usage trends for their network devices. The most common usage is bandwidth usage monitoring, but you can also monitor many other aspects of your network like memory and CPU utilizations.