See this article https://support.apple.com/en-in/HT204025
Before you begin
- Update your iPhone, iPad, or iPod touch to the latest iOS, and your Mac to the latest macOS.
- Set up iCloud on all of your devices.
- Make sure that you’re signed in to iCloud with the same Apple ID on all of your devices.
- If you have a Windows PC, update to Windows 7 or later and download iCloud for Windows.
If you have a device that can't update to the latest iOS or macOS, see the minimum system requirements to use iCloud Drive.
In your screen shot you are using id ending with me.com that is used in older versions , why don't you upgrade your Mac to Mac OS Mojave 10.14.4 see this article https://support.apple.com/en-in/HT201475
Its you choice which Apple ID is to be signed , generally for better results create a web mail account you can use gmail services https://support.google.com/accounts/answer/27441?hl=en
And also create an Apple ID see this article https://support.apple.com/en-in/HT204316
Make sure the Apple ID address and web mail address are kept as same in system preferences > iCloud the Apple ID must be signed in .
When you click on option button in front of iCloud drive the box for desktops and documents must be checked , so what ever the documents you create in www.icloud.com will get synced in iCloud Drive .
Note : you have to create an Apple ID with secondary authentication , later on you convert the id into 2FA ( its your decision ) and also can can create an id say example1@icloud.com
Note : Try to upgrade your Mac with latest versions first check whether your Mac is compatible with latest version , you will always gets benefits of latest iCloud services .