There's some prerequisites to connect Apple Music service to Soundiiz.
What I have to check ?
- Be sure to have an active Apple Music subscription (learn more)
- Have to turn on iCloud Music Library (how to do ?)
- It's currently not allowed by Apple to connect an Apple Music "child account" to a third party service like Soundiiz.
Still have the issue
Apple Music API have an issue when trying to load the translation language file for some languages. If you have for example a blank page after the login process or nothing happened after filled your credentials, please close your browser and change the system language of your device to "English - United States".
Once this done, open your browser and try to do this login process, it should work now. If no, try with another browser, like Firefox or Chrome.
If still not working, unfortunately it's an Apple side issue there as the URL can confirm. They are probably working on it but as it's only happening for some users... could take some time.