how can I put icloud drive icon on iphone screen

There is no longer an iCloud Drive app. iCloud Drive is now accessed via the "Files" app; that should already be on your iPhone. If it is not, the following has instructions on how to reinstall it: Delete built-in Apple apps on your iOS 12 or later device or Apple Watch - Apple Support

You cannot.

Access these files from your Files app.

Access iCloud Drive files from your iPhone and other devices - Apple Support