Preflop
I dont think, anyone will get on you for overcalling here with A3s, but folding and 3-betting are also both reasonable options. The advantage of 3-betting is, it gives you a chance to take it down right now, or at least isolate one of the players and get it heads up, so that its much easier to
bluff postflop.
Flop
You flopped the nut flushdraw, but its a paired board, and for that reason I would also not raise. If someone have trips, they are not folding, and they might put in a 3-bet. And stacking off a draw on the flop against trips is not an ideal situation at all. The reason for this is, they have a redraw to a boat, which cuts into your
equity. And there is also a risk, you might be drawing completely dead, if someone has a boat already with JT, TT or JJ.
Turn
There is an error in your hand history, because on the flop it says UTG+2 folds, but now it says UTG+2 bet. It does matter a little bit, if you are playing against the preflop raiser or a field caller, who took over the betting lead on the flop. But I will just ignore this and analyse the situation, that however bet the flop and got two calls, is now betting again, when the flushdraw completes.
This does not concern me to much, because I think, he might bet again with trips, and certainly with a lower flush. I am also not concerned about J3 or 33, because those hands should not get to the turn like this. Its a freeroll, so maybe they do, but in hand reading we need to make the assumption, that our opponent play an at least somewhat reasonable strategy like not opening UTG or flat calling with J3 and not putting in chips on the flop with an underpair in a 4-way pot.
If you just call here, pot will be around 40BB, and you will have 40-45BB left for the river, depending on who the opponent is. Another spade would be an action killer, unless he has like exactly the K or Q high flush. But it also looks super strong, if you raise here to basically any size. So I am ok with just calling and then praying for a non-spade river, which does not dubble pair the board.
River
You got a perfect blank river, and he jam. This is the easiest call in the world. If he has a boat, its just a cooler. And I think, he could still be jamming worse hands for value like at least a worse flush. Going back to hand reading on the earlier streets, neither UTG nor UTG+2 should be in there with JTo. So the only realistic boats are JJ, TT and JTs, which is only 5-6 combos depending on the suits.
Losing to 5-6 combos is the same as having KK preflop. We just dont fold KK preflop for 55-60BB, and if someone happen to have AA, then congratulations to them. Nice hand sir, see you in the next tournament. Or if they actually can have all the other boats like 33 or J2 offsuit, then they can have a ton of other hands as well. Like maybe they have T2s and think, they improved on the river. Or maybe they are on a complete airball bluff. It is after all a freeroll.