That is correct. WD discovery maps the private user space. The mapped share you have is the default public samba share.
the default public share is there for time machine and windows file history backups but can be used for other devises that need a traditional samba share.
The private user space can only be mapped using the WD discovery app.
Data in the private user space is not accessible via the public share and vise versa. Additionally the mobile and browser access cannot see anything in the public share.