As said before, the Secure Socket Tunneling Protocol integration with UAG is designed to complement the Network Connector. Since NC is only usable on Vista and older operating systems, SSTP provides a similar experience for Windows 7 users. For usability, UAG integrates both into a single application icon on the portal, so by adding "Remote Network Access" earlier, you are covering both. Even if you are using just SSTP, without the Network Connector, you still need the icon on the portal, so go back to Adding Network Connector to the portal and perform the steps detailed there.
The way UAG configures SSTP is complicated, but easy to do. When you configure the SSTP settings in UAG and activate the configuration, UAG pushes the SSTP configuration to TMG, which in turn, pushes it to the Routing and Remote Access Service (RRAS), which is a part of Windows. RRAS itself configures several additional options and services. This is a good opportunity to remind you once again that to use SSTP...