When you reach city 12, 18 points are required to win the World Cup in Road to Rio mode.
I strongly advise finding a like minded booster who is also in city 12 and trading wins with them.
To ensure matchmaking, set controls to manual and use low rated teams. You can quit following kick off to award your fellow booster 3 points. Trade wins until you both have 12 points. Then use the EASFC Catalogue to gift 2 additional games to each other allowing for both players to achieve 6 wins and the required 18 points.
Now it has been suggested that you can be matched with players who aren't in your city but they must be within 2 cities of you. I'll try to confirm this as soon as I can.