It has SBUS/CPPM output pad. Be sure in what mode you are in (Blue Led stay lit indicates XSM in SBUS mode, otherwise in CPPM mode).

General instructions for binding XSR-E(M) receiver are following:

1.Turn on the transmitter while holding the F/S button on the module (please refer to the module instruction
manual for switch positions). Release the button. The RED LED on the Module will flash, indicating the transmitter
is ready to bind to the receiver. Or navigate to [Bind] option and start binding process on the OpenTX menu.
2.Connect battery to the XSR-M receiver while holding the F/S button on the receiver. The LED on the receiver will
flash, indicating the binding process is completed.
3.Turn off both the transmitter and the receiver.
4.Turn on the transmitter and connect the battery. The GREEN LED on the receiver indicates the receiver is
receiving commands from the transmitter.

Have in mind that XSR-E(M) is working in D16 mode. Transmitter shoud be in D16 mode. Also there are EU LBT/FCC firmware versions on TX/RX that will not bind if mixed.

Tried everything ! Please help