At present iZettle Pro is only designed for use with iPad 4 and above, and iPad Mini 2 and above.
Support for iPhone and iPod will be included at a later date.
Reports is the iOS and Android app related directly to your iZettle Pro account. From the smartphone app you can view your account report info such as recorded sales and refunds.
You can find this app on your iPhone or Android smartphone by searching "iZettle Pro reports" in the App/Google Play stores and downloading the app