Call a url when user get reward with Channel Points

Sure but in the API you can ONLY talk to rewards that your clientID created

The problem you are having is that the reward you are trying to talk to was created in the dashboard (or another clientID)

You cannot manage dashboard created custom rewards (including fetching redemptions) via the API

EventSub (and pubsub) however, will notify of all custom rewards.

Then either

Then murilo_rt will use yoru App to create the rewards.

Or

You use EventSub or PubSub to consume redeems in real time.