This can be done without actually playing with other players.
Simply select an online match and after a short wait you will just be placed into a game with 5 other bots. Simply win the game by focusing on destroying a single path of turrets and get to the other base's core.
As for the winning, the bots aren't on the easiest difficulty, and they will manage to get through your turrets eventually, but it should be doable in one go.