System.Net.WebClient

Download from URL with "System.NET.WebClient"

$webclient = new-object System.Net.WebClient
#[System.Net.ServicePointManager]::ServerCertificateValidationCallback = {$true} #If certificate Selfsigned
$webclient.Credentials = new-object System.Net.NetworkCredential($username, $password)
$webpage = $webclient.DownloadString("<URL>")