Migrate from VPP to Apps and Books
If your school or district already has a Volume Purchase Program (VPP) account, you will want to migrate your current VPP account to Apps & Books. Follow the instructions available on the Apple's documentation to migrate to Apps and Books: https://support.apple.com/en-au/HT208257.
The reason to do this is so that all VPP info will be updated and available within Apple School Manager. This is important since VPP will no longer be available starting December 1, 2019. You can learn more about it here: https://support.apple.com/en-us/HT209617.