Manager in all versions works as a web server with a web browser. The cloud and server versions make this obvious.
With the desktop version, Manager packages both together but underneath it functions the same way. The difference is Manager desktop hard codes a particular browser (specific to each computer operating system).
The Windows desktop version of Manager was hard coded to use Windows Explorer in the past. As Microsoft is deprecating that program, newer versions of Manager Windows desktop are instead hard coded to use Webview2. If not installed, it is supposed to be installed automatically.
Without Webview2 installed, Manager Windows desktop will not work properly. To fix this, uninstall both Webview2 and Manager, then reinstall both. To do so, this post may help New Update - #4 by Patch