To use the Cloud counter feature, any camera that was installed correctly will suit. The way the camera is connected to the service does not matter, you do not need additional equipment.
As special cloud analytics modules are used to count visitors, you need to apply a subscription to activate them: Online Pro + Cloud Counter or Cloud 10 Pro + Cloud Counter.
The plans differ only by the option of recording archive to the cloud: Online Pro + Cloud Counter plan does not presuppose cloud archive recording, only short event video clips (up to 10 seconds long) are recorded. With the Cloud 10 Pro + Cloud Counter plan you can choose the type of the archive recorded (detector-triggered, continuous, or delayed recording), the archive is stored in the cloud for 10 days.