When you use iCloud Drive, all the items stored there appear in the presentation manager. Items that can't be opened by Keynote, such as documents from other apps, are dimmed.
With the presentation manager in browse view, tap the link in the top-left corner of the screen to navigate to iCloud Drive (so that iCloud Drive appears at the top-center of the screen).
Depending on the folder you’re in, you may need to tap the link more than once.
Do any of the following:
Search for files: Tap the Search field, enter all or part of a presentation or folder name, then tap Search on the keyboard.
Keynote displays all matches, but matched items that can’t be opened in Keynote are dimmed.
When you are finished, tap an item to open it or tap Cancel to return to iCloud Drive.
Sort the items: Swipe down until you see Name, Date, Size, and Tags buttons, then tap one.
Switch between icon and list view: Swipe down then tap 
in the upper-right corner.
View the content of a folder: Tap the folder.
Open a presentation or a Keynote-compatible file: Tap the file. If the original presentation was in another format (for example, Microsoft PowerPoint), a copy opens in Keynote.