Sending signal through fkysky FS-RM003 tx module to AFHDS2A rx via Arduino/STM32

[BurnEye20]

I am a beginner in radio control and it seems my problem is different than what is stated in this hub.

I have a Flysky AFHDS2A Transmitter and Receiver (FS-RM003 and FS-BS6). Thus, the AFHDS2A firmware is already loaded on the transmitter from the factory.

How do I send signals through the PPM output of the transmitter to the receiver using arduino/stm32?
Should I follow the steps here by opening the tx module and re-flashing it?

Be great to hear back from you. Thanks