Here it is. The first time that i tried installing the IR sensor, I had to reinstall Volumio on my SmartiPi touch 2 player every time that i had to shut down the Pi 4 to select the right GPIO pin for the Single out on the IR Receiver.
I finally found the right GPIO pin, gpio22. I went to the volumio UI in the browser and select JustBoom for the remote profile. Scrolling down to the GPIO configuration, I selected gpio22 and restarted the player. I got lucking, by pressing some buttons on the Remote like volume and noticed on the player, the volume was working. There was a few more like Mute/Shuffle/Random and power buttons worked. Just the play/forward/back buttons don't work.
But, the next day, i turn on the player and that when the IR sensor didn't work, not even the volume on the remote. So one day it works but the next day, it doesn't.