Why I can add folder to `On My iPad` location but I cannot add folder to `On My iPhone` location? On my iPad I can create folders wherever I'm in, but on my iPhone I cannot create folder in the location On My iPhone but I can create folders in side the apps' folders like Acrobat.
iPadOS: 14.2 and iOS: 12.4.8
This is a new feature of iOS 13.
Your iPad is on iPadOS 14.2 so has the feature and your iPhone is on iOS 12.4.8 so does not have the feature.