You said you are using an adapter cable with built-in regulation to 3.3V supply for the sensor.
Therefore the sensor communicates with 3.3V voltage on TX/RX pins, and you need an USB serial adapter with matching 3.3V TX/RX voltage, as using 5V may damage your sensor.
If you can find an adapter which outputs 5V USB supply but uses 3.3V for TX/RX logic voltage, it would be a standalone solution.
You don't generally need the RTS/CTS pins of the USB adapter so they can be cut off, but it depends on which program you intend to use and how it wants to use the RTS/CTS pins and if it requires them to be connected in some way.