Then I can help no further as it works for me.
My last run used this. It uses the mn+1 that I discussed earlier.  I also attached your original workbook with my macros. I like copy paste from files rather than forums as they don't post tab characters.
	Sub Main4()
  Dim pf As String, sfs, sfp
  'Tools > References > Microsoft Scripting Runtime
  Dim fso As FileSystemObject, sf As Scripting.Folder, f As Scripting.File
  Dim ws As Worksheet, fr As Range
  Dim mn As String, fbn As String
  
  'Parent Folder
  pf = "d:\myfiles\t"
  
  Application.ScreenUpdating = False
  Application.EnableEvents = False
  Application.Calculation = xlCalculationManual
  
  Set fso = New FileSystemObject
  
  'Array with Subfolder paths.
  'http://www.vbaexpress.com/forum/showthread.php?58579-get-file-paths-based-on-name-criteria-from-folder
  sfs = aFFs(pf, "/ad", True)
  
  'No error check for subfolder paths put into sfs. At least one subfolder is assumed.
  For Each sfp In sfs
    Set sf = fso.GetFolder(sfp)
    'Copy Template worksheet to new worksheet and with subfolder name.
    If Not WorkSheetExists(sf.ShortName) Then
      Worksheets("Template").Copy After:=Worksheets(Worksheets.Count)
      Worksheets(Worksheets.Count).Name = sf.ShortName
    End If
    'Set worksheet for input: Assumes that each subfolder name has a worksheet name.
    Set ws = Worksheets(sf.ShortName) 'e.g. CSV, XLS, XLSM, etc.
    For Each f In sf.Files
      'Month number from file's date created.
      'mn = Month(f.DateCreated)
      'Month number from file's date modified.
      'mn = Month(f.DateLastModified)
      'Month number from file's oldest date created or date modified.
      mn = Month(WorksheetFunction.Min(f.DateCreated, f.DateLastModified))
      'File's basename
      fbn = fso.GetBaseName(f.Name)
      'Find fbn in month name's column
      Set fr = ws.Columns(mn + 1).Find(fbn)
      If fr Is Nothing Then
        'ws.Cells(ws.Rows.Count, mn + 1).End(xlUp).Offset(1) = fbn
        ws.Hyperlinks.Add ws.Cells(ws.Rows.Count, mn + 1).End(xlUp).Offset(1), f.Path, , , fbn
      End If
    Next f
    ws.UsedRange.Columns.AutoFit
  Next sfp
  
  Application.ScreenUpdating = True
  Application.EnableEvents = True
  Application.Calculation = xlCalculationAutomatic
End Sub