In this page, there are three options for transfer
When you choose the first or second option, the shows list of completed projects. When you click on a project, it automatically fills the Username to which the payment has to be done and the Amount to be sent. When you click on Transfer, the details will be saved and will not be sent to the freelancer. This is just security measure before it is sent.
You need to go to Manage Payments → Outgoing Escrow Payments and Release the payment.