Hi. Im making player classes which will give you specific boosts and upgrades. The problem that you are choosing it in “lobby hub” and it somehow needs to be sent to another experience. Im using Profile Service / Replica for saving player’s class.
Your best option is to use memory stores. This is handled on the server and is much faster than datastores. Memory stores | Documentation - Roblox Creator Hub
Another option is to use teleportdata, however to my understanding none of the options for this is actually server sided so I wouldnt recommend using it. Howver it is worth noting is arguably much easier to get working, but at the cost of not being as good as memory stores
Do also keep in mind that the privateserver code you get when making the second place is NOT the same as placeid etc