With the DJI RC-N1 Remote Controller:

Connect your mobile device (connected to the internet) with the remote controller, and then connect to DJI Mini 3 Pro via the DJI Fly app.

Follow instructions in the app to activate DJI Mini 3 Pro.

With DJI RC:

When using DJI RC for the first time, connect to Wi-Fi or a smartphone hot spot to connect to the internet, and follow instructions in the app to activate DJI RC.

After activating DJI RC, connect it with DJI Mini 3 Pro via the DJI Fly app.

Follow instructions in the app to activate the aircraft.