The manual is kind of a mess on this topic tbh.
There's the main wiring page which isn't complete, and then there is the crossfire page which isn't linked anywhere, and the governor page which describes the rpm wiring. In any case when you flash your receiver you choose what protocol it outputs, you likely want crsf for telemetry support, but it can also do sbus. Setting to PPM makes no sense to me.
See these two pages:
https://manual.spirit-system.com/index. ... sFire_CRSFhttps://manual.spirit-system.com/index. ... ng_exampleOr if you want to use sbus output for some reason:
https://manual.spirit-system.com/index. ... S_RECEIVER