2nd monitor does not resize window when I move from IMac to 2nd monitor.

I have an IMac Retina 5K, 27-inch, 2020, and an HPE243 - Monitor, I connect them via  G2 Thunderbolt Dock. The monitor does not have the USB-C display connection and sometimes i connect my work PC, so i have two of the same HP monitors - which the dock supports (but that is another story).

Anyhow, when I move a window from my IMac Monitor to the HP monitor (since they are not the same size), the window does not resize itself. Super uber annoying. Some have suggested downloading the displaylink manager, which I have - but it does not recognize the 2nd Monitor.

Does any have suggestions?