The new Remote Desktop service is available only in a web browser window. After authenticating with your '@ausport.gov.au' account and doing multi-factor authentication (MFA) you will again be prompted for username and password. Enter the same details again. Note that "_admin@ausport.gov.au" accounts will not work on this service.
You should now use Remote Desktop (RDP) or Putty (SSH) for access to on-premises servers, depending on what is assigned to your account. To logon to a server with RDP will generally require use of an "_admin@ausport.gov.au" account.