The steps are as follows:
1. Open the AppStore, search for, download and install the Kugou Music application. Make sure you are logged in to your Apple ID. Open the Kugou Music app and log in to your Kugou account (not logged in yet).
2. In the Kugou Music app, find the song you want to set as the ringtone. After finding the song, find and click the "More" button next to the song.
3. The system will pop up a confirmation window. Click the "Confirm" or "Settings" button to set the selected song as the ringtone for incoming calls. Open the "Settings" application on your phone and select "Sounds and Touch" or "Sound" option to enter the ringtone setting interface.
4. In the ringtone setting interface, find the "Incoming Call Ringtone" option and click to enter. In the "Incoming Call Ringtone" option, you can see the Kugou Music song you just set. Click on the song. Set it as ringtone.