If the noted player isn't in the game, Cogwork Tracker's last ability won't do anything, although it must still attack each turn if able. This is also true if there is no noted player because Cogwork Tracker was the first card drafted from a booster pack.

If, during your declare attackers step, Cogwork Tracker is tapped, is affected by a spell or ability that says it can't attack, or hasn't been under your control continuously since the turn began (and doesn't have haste), then it doesn't attack. If there's a cost associated with having a creature attack, you're not forced to pay that cost, so it doesn't have to attack in that case either.

If the last ability doesn't apply, you choose which player or planeswalker Cogwork Tracker attacks.

If your draft is breaking up into multiple games, you and the noted player(s) aren't required to be in the same game.

If there are multiple noted players, perhaps because the players on both your left and right passed a Cogwork Tracker to you, you choose which of those players each Cogwork Tracker attacks. If you control more than one, they can each attack a different noted player.