Go to Game Settings -> HUD and GAMEPLAY

UDP Telemetry Settings (bottom of the screen)

UDP Telemetry (DATA OUT) = On​

IP 127.0.0.1

Port 10001

Install the  Loop_back _utility​

Select Forza Horizon 4 -> Save -> Quit utility​
 

PS. UDP Port (default = 10001) can be configured in documents/simracingstudio/config.ini file

PS2. If you have another app using Forza UDP, it won't work since the other App is ​"blocking" the UDP for our app