Spirit System

The frsky integration cable has power, ground and signal cables that connect to the receiver s.port.

Why is a second power connection required?
The receiver is also powered from the sbus cable.

My receiver only has one power connector. R-xsr.

FrSky integration cable can be powered only from side of the receiver. Unit itself is not powering the cable, because there is no power at the SYS port.
Since also SBUS cable must be connected for channel transmission it is powered in this way.
R-XSR require special connection - we have scheme here in the forum for this receiver.