import bpy
bl_info = {
    "name" : "Test",
    "version": (0, 0, 1),
    "description" : "",
    "blender" : (2, 80, 0),
    "location" : "",
    "warning" : "",
    "category" : "Scene"
}

class ThisThingOperator(bpy.types.Operator):
    bl_idname = "scene.tester"        # Unique identifier for buttons and menu items to reference.
    bl_label = "Export tester project" # Display name in the interface.

    prop_directory : bpy.props.StringProperty(
        name="Root Folder",
        description="TesterButton.",
        subtype="DIR_PATH"
        )

    @classmethod
    def poll(cls, context):
        return (context.mode == 'OBJECT')

    def execute(self, context):
        return {'FINISHED'}

    def invoke(self, context, event): # Used for user interaction
        wm = context.window_manager
        return wm.invoke_props_dialog(self)

    def draw(self, context): # Draw options
        row = self.layout
        row.prop(self, "prop_directory", text="Bla")

def menu_func(self, context):
    self.layout.operator(ThisThingOperator.bl_idname)

def register():
    bpy.utils.register_class(ThisThingOperator)
    bpy.types.TOPBAR_MT_render.append(menu_func)
    bpy.types.Scene.directory = bpy.props.StringProperty(subtype='DIR_PATH')

def unregister():
    bpy.utils.unregister_class(ThisThingOperator)
    bpy.types.TOPBAR_MT_render.remove(menu_func)

if __name__ == "__main__":
    register()