On the following screenshot from https://www.apple.com/icloud/icloud-drive/, it looks like I can use an iCloud app on iPhone and iPad. But some webpage such as http://www.imore.com/how-set-and-use-icloud-drive-iphone-and-ipad says that there is no iCloud Drive app.
I hunted every where on the iPhone 5S and iPad Air which both have iOS 8 and has iCloud enabled, but I can't find such screen as in the screenshot below.
So how do I go to the screenshot as below? I upload a PDF file, a picture, and an mp4 file on my Macbook using the Chrome browser on www.icloud.com, but can't access those files just like how I would use DropBox or Copy (which has 15GB free).