You don't have to log into iCloud.com to access iCloud Drive on your Mac. It's much simpler!
Thanks to iCloud Drive, Apple's cloud-based file sharing system, we can share files between Mac and iOS seamlessly. On iOS, you can find all of your files under the iCloud Drive app. On your Mac, everything can be found in the Finder window. Here's how.
How to access iCloud Drive on your Mac via Finder
Click on the Finder icon in your Mac dock.
In the Favorites section, click on iCloud Drive
Alternately, you can find iCloud Drive in the Go menu at the top of any Finder menu if you've removed it from the Favorites section.
Or, you can alway use the keyboard shortcut command + I.
By default, iCloud Drive maintains folders for each of the Apple iWork applications — Keynote, Pages and Numbers — along with folders used by Preview, QuickTime Player, Script Editor, TextEdit and Automator. With macOS Sierra, iCloud Drive also stores all of your Mac's desktop files and everything in your Documents folder. But that doesn't mean those are the only folders you can keep in iCloud Drive. You can put whatever you want in there, within the limits of your storage allotment for iCloud.
Treat iCloud Drive as you would any other remote volume, like an external hard disk or a network drive. You can create new folders inside iCloud Drive, or just drag and drop files and folders from existing locations on your Mac into iCloud Drive.