It's less about the type of iPad than it is about the iOS version on the iPad.
You may use any iPad that has iOS 11 or above.
Starting April 8th 2020, ProductionPro will no longer be supporting iPads with operating systems under iOS 11. If you are using the following iPad models, you will no longer be able to update to new versions of the ProductionPro iPad app:
Original iPad mini
You may continue using the ProductionPro iPad app currently on your iPad or access ProductionPro on the Web.
If you have newer iPads (than those listed above), please upgrade your operating system to iOS 11 or above to continue getting updates for the ProductionPro iPad app.