Hey there, aniovira.
Welcome to the Apple Support Communities! Thanks for posting about the issue you're having with uploading information to iCloud Drive. We'd be glad to see what we can do to help.
You mentioned receiving an error about a plugin not functioning as expected. You posted your reply in the iPad thread on the board. Are you using your iPad to attempt this upload? If so, what is the exact text of the error pop-up that you see when attempting this? Does the same issue occur if you try to upload this file through the iCloud webpage? If you've not tried, check out the Upload and download files from iCloud Drive on iCloud.com guide and see if the same issue occurs.
Let us know what you find out.
Take care