How to make compatible

You can't download YouTube with the 2nd Gen iPad. YouTube requires iOS 11 or later and the iPad 2 cannot be upgraded past 9.3.5. You will have to buy a newer device.

Neither the Gen 3 or 4 iPads are compatible with software later then iOS 10.3.4 because iOS 11 is a 64-bit software and the iPads 2, 3, and 4 all have 32-bit hardware.