Hello Cedric Robertson,
Welcome to Apple Support Communities. We understand that you're having issues downloading files from iCloud to your Mac, and also, uploading files from your Mac to iCloud. We understand the importance of getting this issue resolved, and we'd be happy to look into this with you.
Which Mac model, and macOS are you using? You can find this information when you navigate to the Apple symbol at the top left corner of your screen, then go to "About".
Does the issue persists when connecting to another Wi-Fi network?
Please check out these helpful links:
Set up iCloud Drive
Access and manage files in your iCloud Drive
We hope this information is useful. Kind regards.