After installing "QuickPlan for macOS" from the Mac App Store, the macOS will also create an iCloud Drive folder for QuickPlan, all the files in the folder will be sync automatically to all the other devices with the same iCloud account (iOS and macOS control the file synchorization).
QuickPlan supports to access the .qpp file in the QuickPlan iCloud Drive folder directly, and the changed file will be sync to other devices automatically.
Our practice is to work in a working folder out of the iCloud Drive.
We may make a mistake to change the project incorrectly, and the changes may be automatically synced to other devices before we realize the problem - this is out the control of QuickPlan. To avoid spreading incorrect changes to other devices before checked: