The Apple Music authentication made by Apple could have some difficulties loading from time to time (there is nothing we can do on our side for that, unfortunately). If you got any issues with it, we recommend you temporary disabled your browser extension. If still not working, give it a try with another browser/device or network.
Be aware "child" Apple accounts are not allowed to use the "Apple Music API" so the authentication process will fail. Same for "Curator" Apple Music account.
The authentication process to connect an Apple Music account inside the Soundiiz Android App could also fail. In that case, we recommend you use the Google Chrome browser directly instead on your Android device and go to https://soundiiz.com/webapp to connect Apple Music to your Soundiiz account from there.