As per USB 2.0 protocol, it is a host centric/ host initiated protocol. Even though the hardware has data, host must keep polling it for retrieving the data from the device. That is how the USB spec is defined. Thus as you understood, in case of CY7C68013, host must keep polling for data fro device.
Note: Asynchronous notification by the device to host is an improveent of USB 3.0 spec over USB 2.0 spec.
Please let me know if you need further clarification or any other documentation for getting started with FX2LP (CY7C68013).