The Sony Xperia XZ1 Compact is explicitly listed as being compatible. However, in the Play Store it cannot be downloaded (not compatible).
Could this be due to the recent update to Android Pie?
The problem happens because of the Android version. A customer has replied that he could download the app with Android 8. However when he used his wife's phone (Android 9), the app could not be downloaded. Hope Google could fix the bug asap.
You could follow the issue on Google's forum: https://github.com/google-ar/arcore-android-sdk/issues/639