Hey Tjelden,
Thanks for using Apple Support Communities for the issue you're having with editing files using iCloud Drive. We want to help! First, be sure that your Windows software is updated, then check for Apple updates. Here are some guides that can help:
Windows Update: FAQ
How to use Apple Software Update for Windows
After installing available updates, see if you're able to then edit those documents without issue. You may also want to disable any security software you have installed as they can block access and cause odd issues to occur.
We thought the following resources would also be helpful when using iCloud Drive:
iCloud Drive FAQ
Work with files and folders in iCloud for Windows
Let us know how that go
Take care!