iCloud & iCloud Photos · iCloud Drive basics
How do I download all my iCloud Drive files to my Mac?
Short answer: Turn off Optimize Mac Storage for iCloud Drive, then right-click folders in Finder and choose Download Now or Keep Downloaded. Check your free space first — Storage Studio can move other big folders to an external drive to make room.
Turn off Optimize Mac Storage in iCloud Drive's settings, then right-click the folders you want in Finder and choose Download Now (or Keep Downloaded on recent macOS so they stay local).
Before you do, check you have room: open Storage Studio's Storage Profile or macOS's System Settings → General → Storage to compare your free space with the size of your iCloud Drive.
If space is short, make room first — for example by relocating big apps or non-synced folders to your fast external drive with Storage Studio — so the download doesn't fill your startup disk.