I tested another lib for the RF remote control.
I use the RC switch from this link.
https://github.com/sui77/rc-switch
It is pretty easy by changing the initial pin to pin PA7( or other pin).
mySwitch.enableReceive(PA7);
Received 5592332 / 24bit Protocol: 1
Received 5592512 / 24bit Protocol: 1
Received 5592323 / 24bit Protocol: 1
Received 5592368 / 24bit Protocol: 1
From the “Receive Demo.pde” , The output from Serial is above for button A , B , C ,D.
Have Fun.
I have used it several times on AVR for both sending and receiving, and I have contributed to the forum for that lib as well, as I worked out how to use it was the WattsClever remote controlled mains sockets
Code
#include <RCSwitch.h>
RCSwitch mySwitch = RCSwitch();
.
.
.
mySwitch.enableReceive(PA7); // Receiver on interrupt 0 => that is pin PA7
//НАЧАЛО бесконечный цикл while (true)
while (true)
{
if (mySwitch.available())
{
tft.print(F("!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!"));
output(mySwitch.getReceivedValue(), mySwitch.getReceivedBitlength(), mySwitch.getReceivedDelay(), mySwitch.getReceivedRawdata(),mySwitch.getReceivedProtocol());
mySwitch.resetAvailable();
}
}
If not, your rx or tx could be fully off the frequency..
Do you power the MX-RM-5V with 5 or 3.3V?
Or, put a 3k3/2k2 resistor divider in the series with Maple input.
Then you may start to mess with software.

and why is incompatible, first time i see it
Maybe RCSwitch LIB support only some protocols, and do not show what received unsupported protocol?
if (mySwitch.available())
must triggered after received something.?????