Why are you using a WebBrowser to code a file explorer?
The URL property of a WebBrowser control is a
class instance, not a
: WebBrowser.Url Property (System.Windows.Forms) | Microsoft Learn
You can construct a Uri using a string:
Uri uri = new Uri(myString);
But quite what it will fo with a "raw" folder path, I'm not sure - probably complain because it isn't supposed to open them.
I think you need to work out exactly what you expect this to do, and then think about how to go about it - because I don't think a WebBrowser control is the right tool for the job, whatever that job is!