Tick The Check Box Of Desktop And Documents On the next screen make sure to click on the check box regarding desktop and documents folder.After the check option at the right side top you can see the options bar>click on it.On the next screen, you can see the iCloud drive with a check box make sure to check the box.After signing in, a screen displays about iCloud make sure to click on NEXT.
However, if you are already signed in it allows you otherwise you need to type your Apple ID and password to access the iCloud.In the system preferences, you can see so many apps and files appear on that in that click on iCloud.