This code is sufficient:

Sub M_snb()
  With Application.FileDialog(4)
    .InitialFileName = Application.DefaultFilePath & "\"
    If .Show Then c00 = .SelectedItems(1)
  End With
    
  With CreateObject("wscript.shell")
    For Each it In Selection
      c01 = c01 & vbLf & .exec("cmd /c dir """ & c00 & "\*" & it & """*.* /b /s").stdout.readall
    Next
  End With
    
  MsgBox c01
End Sub