The second paragraph of the first screen capture tells you what the most likely problem is. Windows doesn’t like a user using two or more different user names to access a password protected network device. Couple of suggestions. Disconnect any mapped network shares to the network attached storage. Check the Windows Credentials Manager and remove any entries for My Cloud or Western Digital.
If you are using a My Cloud Home device see the specific subsection for teh My Cloud Home device as this subforum (My Cloud) is generally for the single bay My Cloud device which is different than the My Cloud Home line of devices.
turned to support with the same problem.
Answered that the problem in the latest patch Windows and the HP at the moment there is no solution to this problem
Unless there is another problem, the error message you are seeing is a standard, long-standing Windows issue with mixed credentials when trying to access a common network resource.