On-Demand is a feature that allows you to access your entire collection of files stored in the cloud using File Explorer without having to download them first to your device.
However, you’ll need an internet connection to open files that you don’t explicitly make available offline, or you didn’t already open.
You can enable OneDrive Files On-Demand using these steps:
5. Under “Files On-Demand,” check the ‘Save space and download files as you use them’ option.
Once you complete these steps, OneDrive Files On-Demand will be enable on your device. This should be done before syncing any shared files. If you sync shared files when the files are not on demand. Your hard-drive may fill up.