How to create a public match that people can find from a server browser using Unreal Engine?

I have followed the shared spaces example and I have a game that has multiplayer with private matches and one public room, but I'm not sure how to have a user create a separate instance of the public room so that there is more than one public destination. Does anyone have any tips on how to achieve this?

The shared spaces example says "There is currently only one purple room, which is a scheme that doesn't scale in real life. Public rooms should be handled using a matchmaking system to distribute players into separate instances for load balancing".