This is most likely caused by a firewall blocking the browser from loading. Go to your firewall settings and make sure to allow it. PPTWebBrowser shows up as different names depending on your firewall. It can be DotNetBrowser or PPChromium.
PPTWebBrowser needs to be installed on the computer giving the presentation for it to work. You can log into your account and download and install the latest release of the plugin from your order history.