How to set up an in-game store like in Paragon (Newbie Question)

Hello! And thanks for reading my question! I was wondering how do developers set up a store and different currency systems. For example, Paragon with its reputation currency and its coins(cash currency). Do they do it within the engine with blueprints and such, or do they use another piece of software, etc. Also how do they transfer the funds from the developers to the customers’ account(s), considering it’s a digital currency. Lastly, how does the signup process work from their end? Because as gamers, we know the whole shtick as signup, download and play, but how do the developers even go about setting up that entire process, and maintaing their database(s)? As you can tell I’m new to this side of the industry so any insight is greatly appreciated! :smiley: