Hello Ben,

Welcome to the Forum!

This macro will search a folder for all files that have match this pattern "_yy/mm/dd.txt". The matching files will be listed on "Sheet1" starting with cell "A1". Change the worksheet and file path in the macro to what you want to use. They are marked in bold.
'Written: July 14, 2010
'Author:  Leith Ross
'Summary: Lists files on a worksheet in column "A" that match a pattern.

Sub ListFileNames()

  Dim FileName As String
  Dim FilePath As String
  Dim Valid As Boolean
  Dim Wks As Worksheet
  
    R = 1    'Starting Row
    Set Wks = Worksheets("Sheet1")
    FilePath = "C:\\My Documents\" & "*.txt"
       
     FileName = Dir(FilePath)
     
     Do While FileName <> ""
       Valid = FileName Like "*_##/##/##.txt"
         If Valid Then
           If Mid(FileName, 6, 5) = Acct Then
             Wks.Cells(R, "A") = FileName
             R = R + 1
           End If
         End If
       FileName = Dir
     Loop
     
End Sub