In your Windows Explorer/Finder you have two options of keeping your folder/files locally stored.
Download folder and start/stop synchronization. See below.
Download folder is downloading all files in a folder.
This is making the files available in offline usage.
Start/Stop Synchronization is also downloading your files, but also if you or another user add folders/files to the folder, will the system automatically download the files to be stored locally for offline usage.
Start/Stop Synchronization can also be enabled on a share, this will keep all folders/files available for offline usage.