无法使用PowerShell在SharePoint server上验证和下载Word文档列表

我有一个脚本,可以从SharePoint服务器检索到具有指定文本的Word文档的所有链接。文档列表复制到本地驱动器后。

$siteAddress = "http://d/D/O%20S/S/O/S/"
$invokeData = (Invoke-WebRequest -Uri $siteAddress -UseDefaultCredentials).Links.Href| Select-String "/Dev/O/S/OS2017-1/S/"
foreach ($item in $invokeData)
{
  $filename = "http://docs" + $item
  $ssLDocName = Split-path $item -Leaf
  $ssLDocName2 = "D:\FF\" + $ssLocalDocName
  $userName = "John Doe"
  $passWord = Get-Content D:\Password.txt | ConvertTo-SecureString
  $C = new-object -typename System.Management.Automation.PSCredential -argumentlist $username, $password
  Start-BitsTransfer -Credential $C -Source $filename -Destination $ssLocalDocName
}

当我执行它时,我得到了错误消息

Start-BitsTransfer : HTTP status 401: The requested resource requires user authentication.

我认为这是一个错误登录的问题。我尝试了不同的品种。没有运气。