Hello, yes, it's just a random picking generator.
About your screen, let's give you an example :
Taking a player that will open the GUI and bet 10 and roll a number 8887.
From the default config file:
-if you are using ServerReward this player will win 3 points per point the players bet because the "win list" contains "888x", 30 points win in total.
-If you are using Economics this player will win 15.6 $ because the win list contains "888x" : 56 where 56 is the percent of the total bet amount.
If he were betting 10 000 but rolled 1256, he will just don't won anything because the win list set in config just don't contains any price for this combination.
If you want to give more chance to win to your player, you have to lower the range number by chaning "RollMinRange" and/or "RollMaxRange"
Just hope it's more clear, i had try to exmplain everything in the plugin description, but the mechanic is a bit complexe.