Must have flight battery / BEC plugged in for the RC receiver to be powered. It does not get power from "USB only".
You need a Flight Mode Switch, or the stick animations don't work, but the rest works even though you don't see it.
Your RC receiver must be configured for the protocol you want it to put out. It must also be connected with a correct (often hand made) cable to the correct port (e.g. SBus only works on MainPort on most FCs).