It’s easy to make these PDFs available in Acrobat, and you can quickly configure many apps and device features so that Acrobat is an integrated part of viewing, sharing, and reviewing workflows.
Here we will discuss about Apple’s Files app:
The iOS Files App (iOS 11+) allows you to easily find, organize, and manage all your files.
Available files include not only local files on your device, but also files on other iOS devices as well as cloud services such as Adobe Document Cloud. Adobe DC mobile app support for the Files app means you have greater control and ease of access for all your files and scans no matter where they reside.
Note: This article is specifically representing the Adobe Acrobat Reader mobile app on iOS. As "Files App" is an iOS feature only.