To unlock "Welcome to the League", you need to acquire 2000 FUT Champs points in Ultimate Team and register for WL. These require you to play the online rivals mode. There are two sources:
- Play a game of rivals and you get a few points after the game. The amount of points depends on your division. A win in div 06 means 50 points, while a div 03 win yields 125 points.
- Finish high enough in weekly rivals seasons. You get a few points in the higher rewards tiers. Div 06 rank I and II yield 100 and 50 points.
When you accumulated 2000 points, you have to register for Weekend League to pop the achievement. If you manage to finish at least silver 1 (11 wins out of 30 games from friday morning to sunday night), you get your 2000 points back with weekend league rewards the next thursday.