I assume you are referring to how you can view the pdf files saved in iCloud Drive on Adobe Acrobat Reader mobile application?
If this is the case, then you can easily manage to view your iCloud files in Acrobat Reader app.
Make sure that your iCloud app allowed to access through the Acrobat Reader app and for that you may check.
Settings>iCloud>iCloud Drive>Adobe Acrobat is turned ON
Then go to Adobe Acrobat app>My Document>Click on drop down arrow> Tap More Locations>iCloud Drive
You can select the document saved there.
Hope this is what you are looking for.