
If one of the tokens somehow is under another player's control as the delayed triggered ability resolves, you can't sacrifice that token.If the effect stops the token from attacking a specific player unless a cost is paid, you don't have to pay that cost unless you want to attack that player. If an effect stops a token from attacking a specific player, that token can attack any player or planeswalker, or not attack at all.If there's a cost associated with having it attack, you aren't forced to pay that cost, so it doesn't have to attack in that case either. If one of the tokens can't attack for any reason (such as being tapped), then it doesn't attack.
Each token must attack the appropriate player if able. Effects that modified that creature when it was previously on the battlefield won't be copied. The tokens copy only what's on the original card. Opponents who have left the game aren't counted when determining how many tokens to create. They can't try to remove the card from your graveyard to stop you from paying the cost. Once you announce that you're activating it, no player may take actions until you've finished. Exiling the card with encore is a cost to activate the ability. Sacrifice them at the beginning of the next end step. “Encore ” means “, Exile this card from your graveyard: For each opponent, create a token that’s a copy of this card that attacks that opponent this turn if able. 702.141a Encore is an activated ability that functions while the card with encore is in a graveyard.
From the Comprehensive Rules (November 19, 2021- Innistrad: Crimson Vow)