Excel Autosave to iCloud

You can’t. The autosave feature of Microsoft Excel does not work with iCloud, it works with Microsoft’s One Drive. You must manually save your Excel files to iCloud.

from the internet...

Microsoft's native AutoSave feature does not work with iCloud. AutoSave is built exclusively to integrate with Microsoft's cloud services, such as OneDrive and SharePoint. If you save or edit an Excel file directly inside iCloud Drive, AutoSave will be disabled or unavailable, and you must save your changes manually.

Submit feedback to Microsoft requesting the option. That’s all you can do.

lkrupp wrote:

Didn’t cross my mind. Thanks for the tip.

Yep. A common resolution for a misrouted Microsoft technical support question can be “use something else”, but Microsoft users do tend to either have very specific and more complex and often IT- and business-focused needs — and such requirements are usually also better served by migrating to the native Microsoft platforms Windows and Azure longer-term — or the users can be unaware of the available third-party alternatives to the Microsoft tools.

Here, I assumed the latter.

jpdarnall wrote:

How can I autosave excel files to iCloud?

Open the Microsoft Excel .xsl document using Apple Numbers app.

Didn’t cross my mind. Thanks for the tip.