

To clean things up, you will want to sign in to and delete anything you don't want syncing down in the short term. If you opt in to syncing on one Mac - now you have 4 folders on any one Mac signed in to iCloud - the cloud version of desktop and documents and the local version. Look for confusion around Documents and Desktop.It doesn't do the calculation first - it actually downloads. That means Apple downloads everything and then frees up space when it sees you have little space left. Look for words like "if there is space" in the description.

I think that dialog you have up is pretty clear but based on the last question I would encourage a couple changes in how you're using iCloud.
