Use the .NET or Windows API instead.
I know that The Building Coder has implemented and documented such methods. Don't know where, though, off-hand.
By the way, similar questions have also been discussed right here in the past, e.g.,
https://forums.autodesk.com/t5/revit-api-forum/folderbrowserdialog-in-revit/m-p/8370066
Please always search before asking.