First one needs to pay the money. In the DJI store with the following account:

• Account: [email protected]
• Password: cuhkszdji2021

Last time I paid for RTK is around Sept/2023, it will last for on year, the price is around 900 RMB

If you cannot connect to RTK, try to connect the smart controller to your phone’s hot spot,. Public WIFI usually fails.