Tonal Tinnitus Therapy doesn't collect any personal data.
You don't need an account to use the app.
You don't give any personal data to the app.
The app doesn't need any special permissions.
When you purchase the app license, the purchase is handled by Google Play if you downloaded the app from the Google Play Store. If you downloaded the app from the Huawei AppGallery, the purchase is handled by Huawei.