Go to the school's RHB Hub homepage, accessible here.
Click on the SharePoint Drives icon, or go to https://gdsto365.sharepoint.com/sites/RoyalHigh/SitePages/Home.aspx
Click on the desired shared area on the left hand side. Chose your desired folder within it, then select Sync.
From the pop up that appears, select Open to launch the OneDrive app, which will then start syncing your selected SharePoint folder to your computer.
Open File Explorer on your computer (if using Windows), the yellow folder icon.
You will see Girls Day School Trust listed on the left hand side, with your synced folder listed underneath.