You may use HTML5 based noVNC integrated in Virtualizor Panel.
You also can use a third-party VNC viewer. For a third-party VNC viewer, please use the VNC IP address and the port number given by the page of VNC in Virtualizor Panel, and the VNC password you set in the panel. A username is not needed for VNC. If you want to change the VNC password, after the password is changed, you should power off the VPS hosting, and then start it.