The css (/includes/template/YOUR_TEMPLATE/css/checkout_one_confirmation.css) for the plugin's confirmation page should be doing that already. Did you copy that file to your store's active template's directory?
those files are in the includes\templates\responsive_classic\css folder.
Here is a photo of the process. The circle spins and spins for quite a while while the Confirm button appears at the top right with a zen cart banner appearing too as pictured.