Steps for Synchronizing SharePoint Document Libraries
1: Open your web browser and go to the SharePoint website.
2: On the left side of the web page, locate and click on Documents.
3: If you want to sync the full document library, click on the Sync icon at the top of the screen. You should see a pop-up window prompting you to allow the OneDrive app (click always and OK) and a pop-up window notifying you that your files are being sync’d.
4: Open File Explorer and you should see your SharePoint site.