Function to Check for a SubFolder - Create, if it doesn't exist

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Function MyCreateSubFolder(ByVal sPath As String, sSubFolder As String)
    
    Dim oFile As Object, oFSO As Object, oFolder As Object
    Dim bFoundSubFolder As Boolean
    
    'Set the Boolean Default
    bFoundSubFolder = False
 
    'Set the objects required for File Review
    Set oFSO = CreateObject("Scripting.FileSystemObject")
    Set oFolder = oFSO.GetFolder(sPath)

    'Loop through each of the Sub Folders in the Path requested
    For Each oFile In oFolder.subfolders

        'If the desired subfolder was found, change the boolean
        If oFile.Name = sSubFolder Then bFoundSubFolder = True
    Next
 
 'If the sub folder was NOT found, Create it
 If bFoundSubFolder = False Then MkDir sPath & "\" & sSubFolder

End Function

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Method for calling the function

There is probably a reason you are checking to see if a Sub-Folder exists.
This code will call the function, create the Sub-Folder if it DOESN'T exist, AND Save a file in the Sub-Folder created.

Sub [call function example]

Sub MoveTabToNewBook_SaveInSubfolder()
Dim sThisWorkbook As String, sFilePath As String, sNewSubFolder As String, sFileName As String

sThisWorkbook = ActiveWorkbook.Name
sFilePath = ActiveWorkbook.Path
sNewSubFolder = "Archive Files"
sFileName = "Did_It_Work"
    
    'Move the sheet to a new book: (Move - not Copy)
    Sheets("Visual").Select
    Sheets("Visual").Move
    
    'Check to see if the Sub-Folder Exists (Create it if it doesn't)
    Call MyCreateSubFolder(sFilePath, sNewSubFolder)
    Debug.Print "The Archived files are here: " & sFilePath & "\" & sNewSubFolder
    
    'Save the File (Standard Excel format)
    ActiveWorkbook.SaveAs Filename:=sFilePath & "\" & sNewSubFolder & "\" & sFileName & ".xlsx", FileFormat:=xlOpenXMLWorkbook, CreateBackup:=False
    
    'Close the new file that was saved
    ActiveWindow.Close
    
    'Return to the original workbook
    Workbooks(sThisWorkbook).Activate

End Sub