Since Procreate just had a recent update to iPadOS 13, if you have access to a full computer, you could download, install and use an older version of iTunes on a full computer that will allow you to purchase apps from the iOS App Store within this older version of iTunes.
Back on your iPad, launch the iOS App Store app and tap on the tiny account icon at the upper right corner of the iOS App Store main screen and then tap on Purchases to see if the Procreate app appears there.
Then tap on the app and see if the iOS App Store will allow you to install the last compatible version of the Procreate app.
The version of iTunes for a Mac or PC that you need to download, install and use is available here in my link with more complete procedures
https://discussions.apple.com/docs/DOC-13282
Best of Luck to You!