Do i need a resistor to hard wire my Ring Doorbell?

I have bought a plug in 240v power supply adaptor with an output of 24v AC and 500MA that says i just need to connect it to my Ring doorbell and plug it in, nothing about the resistor. I've never had a hard wired doorbell, always had wireless ones so using existing wiring isn't applicable. So do i just plug it in and off i go or do i have to have the resistor? If i upgrade to the Ring doorbell Pro, will my plug in power source be sufficient?