I am sorry to hear that you are experiencing problems.
When you plug you USB to serial port adapter, make sure that TC-08 is not connected. When the USB to serial port is plugged in to the USB port on the PC the it should be registered as a COM port in the device manager. Check this is happening if it is not it is possible that the USB to serial port adapter is not installed correctly.
If the device is registered as a COM port us this number in Picolog when configuring the TC-08.