Look at the Help of Acrobat Reader.
Would you please tell us which mobile devices you have? iPad/iPhone, Android tablet/phone, or Windows Phone?
- iPad/iPhone: Adobe Acrobat Help for iOS: Managing files and folders
- Android tablet/phone: Acrobat Reader Help for Android: Managing files and folders
The important point to note is that you need to switch the file location to Local (for the documents stored on your device) or Document Cloud (for cloud documents) first. It's not possible to perform some operations (such as Rename, Duplicate) in the Recent section.
Please let us know if you have additional questions.