Can't access entirely shared HDD on Windows Server
Accessing Window's shares on macOS is actually pretty simple but you must follow a couple of Windows login rules.

Set a username and password for the account you want to access the drive on that Windows server and give it the appropriate permissions on that server. It sounds like it should be in the Administrators group, but your choice.
When you connect to the PC from your Mac and it asks for a username and password you must &quot;Fully Qualify&quot; the username like this: [DOMAIN] \ [USERNAME]

I am assuming here that you are using an AD Domain account to access the Windows server which is Microsoft best practices for a Windows DC. For example.
Say I have a server in an AD (Active Directory) Domain and the domain is called &quot;Americas.&quot; I would create the user I want in the Americas domain and give that account the appropriate permissions on the server in question. If we assume my AD username is &quot;stevec&quot; and my password is &quot;123456&quot; then I would log onto that server like this:

Username: americas\stevec
Password: 123456

For completeness sake if you need to access a server (or really any Windows PC) that is not in a domain you preface your username with the name (formerly called the NETBIOS name) of the PC on the network, a backslash, and then your username on that PC.