Upload all PDF files in a folder to a website using VBA

Question

I am trying to upload all the files in a folder to a web portal (all files are PDFs of invoices) using VBA. I have the code sorted to enter usernmae and password sorted and then click "Login" button. That opens to a new page to where files are to be uploaded, the default method is "Drag & Drop".

This is the code I have so far

Sub InvToBkpr()
Dim sFormData As String, d As String, ie As Object
Dim sPath$, sFile$
sPath = ThisWorkbook.Path & "\Boekhouder_PDF\"

Const URL$ = "https://portal.pecco.be/Account/Login/"
Set ie = CreateObject("InternetExplorer.Application")


With ie
    .Navigate URL
    .Visible = True
    Do Until Not .Busy And .readyState = 4
        DoEvents
    Loop
    .document.getElementByID("UserName").Value = [PtlUn]
    .document.getElementsByName("Password")(0).Value = [PtlPwd]
    .document.forms(0).Submit
    Do Until Not .Busy And .readyState = 4
        DoEvents
    Loop

'Code above works fine to open Outlook, insert username & password then login
'PtlUn and PtlPwd are named ranges in my workbook containing the necessary usernmae and password
'Code below is where I need to upload all the files from folder to website

    sFile = Dir(sPath)
    Do While Len(sFile)>0
        '??????
        '??????
        sFile = Dir
    Loop
End With

End Sub

This is a screen shot of the Upload page which opens after successful login, files need to be uploaded to the "Sales" section, as far as I can make out the ID for that element is "fileuploaderSales".

I have tried to modify the answer to this

Uploading File To Website

But without success.

Any help greatly appreciated. TIA