Sync SharePoint files and folders

Sync the files in your Office 365 or SharePoint site libraries so they’re always available on your computer, even when you’re offline.

Set-up sync

On the SharePoint site that you want to sync files from, click Sync.

Note: If your browser asks for permission to use OneDrive, confirm that it's OK.
Sign in to OneDrive to start syncing your files and finish OneDrive setup.

Work with your files in your file system

Once synced, your SharePoint files appear in File Explorer under the name of your organization, or in Mac Finder if you're using a Mac.
Each location will appear in a separate subfolder.
Copy or move files from your computer to SharePoint right from your file system.
To check the status of your files, add an account, or manage other sync settings, click the OneDrive cloud icon in the Windows notification area.

Source: Microsoft