If the error shows 【Linking failed】, you can link Apple ID through your iPhone/iOS device settings.
Open 【Settings >【User Name >【Payment and Delivery】 > 【Add Payment Method】>【Go to TNG for Verification】>【Activate Payment Authorization Service】.
If you have any other issue during this process, please contact Apple Support:
https://getsupport.apple.com/.
If the error shows [Something went wrong]. It might be the network issue, please try again later.