You can either use the SocialGameMode (not too much content there), or manually add it to your existing gamemode blueprint. Post screenshots if you need more specific instructions. If you have trouble to setup structure variables, you might have to recreate the structure, sometimes if a node does not connect, remove a function and readd it anew. The social component goes into your existing playercontroller, and for the setup look into the social player and controller bps. There are also UMGs (widgets), which you can find via the search inside your HUD (basically a widget with your custom UI interface), add the chat window, player and party frames there too.