The sport event becomes available after reaching 3/4 stars in the mall. After that, a pop-up appears and the event icon is unlocked.
When the event is initiated, the player has 3 days to reach the furthest level they can - each round requiring specific items generated by the sport generators on the event board. After the 3 days are over, the player can then collect the sport event rewards on their mainboard (which will help them obtain the gold medal - the requirement for reaching 4/4 mall stars).
It should be noted that any items obtained by the event will not be asked for during normal gameplay. If the player no longer wishes to play the event, they can sell the event-related items. It is also not required to reach 4/4 stars in the mall to further progress in the game.
Lastly, the sport event is a permanent event - the players can play it as many times as they'd like.