No. It should be the credentials used to access the MediaVault. This may depend on how MediaVault was configured.
Read the following from the MediaVault FAQ:
User Mode vs. Workgroup Mode
There are two ways to set up passwords on the HP Media Vault. The easiest way is to set up a single password for each upper level Shared Folder in Workgroup mode. A more complicated, but more flexible way is to set up users and assign privileges to each user with respect to each share, such as Read, Read/Write, or none. Setting up users requires a lot more work for the Administrator and so if you can achieve what you need with Workgroup mode, that would be much easier. You can switch from Workgroup mode to User mode at any time, but when you switch out of User mode, the user list is lost and would need to be re-created if you switch back again.
If you are ever prompted for a User Name while operating in Workgroup mode, use the name of the password-protected Shared Folder you wish to access.