The MCA application works with an audio card only.
It is not possible connect “pulses” coming from a 433 transmitter.
The only method to transmit pulses via radio is to use an audio signal.
1) Send pulses with an FM hi quality transmitter
2) Receive pulses with an FM radio receiver connected with the AUX input of the audio card
(or the Theremino SDR app)
3) If required use some method to send audio signal from an app to another app
(for example the VbCable you can get from internet)