Cloud Drive files aren’t fully synced by default; only the files you are using are synced. You can Force Sync your files however. Right-click the folder you want to make “Offline” and choose “Enable Offline Access (1). Once this is done, you can click your drive icon (2), and then choose “Force Sync All Offline Folders” to sync any folders you have enabled for Offline Access.
Likewise, you might want to pause the synchronization of files while you are dealing with them. This should be possible from the Cloud Drive icon as well. In the menu, choose “Pause Syncing” (3) temporarily stop files from synchronizing. The benefit is that you can keep modifying documents (drafts) locally until it is all together done and afterward you can uncheck the “Pause” and connect to the Drive24 cloud drive to upload any changes.