I’ve transferred data and photos to a new iPad 6. Apps did not transfer. How can I retrieve the apps?

Apps are not directly transferred between devices. For Apps, the transfer process creates a record of the Apps that are installed on the donor iPad - and it is this record of installed Apps that is transferred to the target device. For Apps that are still available for download from the App Store, the corresponding Apps are automatically downloaded and installed from the App Store.

Not all Apps will necessarily continue to be available. Apps may have been removed or retired from the App Store by the respective App Developer. Some Apps may have been abandoned - and may not be compatible with the new device. Where a compatible App is not available, you’ll not be able to transfer/install the App. 

What was the original source iPad version? Apps now only download from the App Store. Some older apps are completely discontinued by the developer. It’s been years since apps themselves were stored in the (then) iOS backup files.

Trying to transfer my apps on this phone