Log into OneDrive via the browser at onedrive.live.com
On the left navigation pane, under OneDrive, select Shared. Files and folders that you can add to your OneDrive are marked Can edit.
Locate the folder you want to add, select the circle in the folder's tile, and then select Add to my OneDrive on the top menu. Or right-click a folder and select Add to my OneDrive.
These files will now appear under “My Files” and will also be available from the desktop version of OneDrive.