You'll need to use PoE to power the ERX, and in that scenario: Yes.
UAP-AC-Lite Power Injector --> ERX Port 0 --> ERX Port 4 in passthrough mode --> UAP-AC-Lite
You'll need to use PoE to power the ERX, and in that scenario: Yes.
UAP-AC-Lite Power Injector --> ERX Port 0 --> ERX Port 4 in passthrough mode --> UAP-AC-Lite