Guacamole VNC Connection Asking for Windows Login on First Connection

[Praneet Negi]

Hi Team,
I am using Apache Guacamole to connect to a VM using the VNC protocol.
In the Guacamole connection settings, I have already saved the Windows username 
and password under the Authentication section.
However, when I connect to the VM for the first time, it still asks for the 
Windows login credentials on the VM screen.
Could you please help me understand why this happens and how can I resolve this?
Looking forward to your guidance.
Thanks,
Praneet Negi