PokerStars Pot-Limit Omaha High, $0.50 BB (8 handed)

CO ($30.10)
Button ($38.35)
SB ($46.35)
Hero ($50)
UTG ($51.65)
UTG+1 ($14.40)
MP1 ($49.75)
MP2 ($33.10)

Preflop: Hero is BB with , , , .
4 folds, CO calls $0.50, 1 fold, SB completes, Hero checks.

Flop: ($1.50) , , (3 players)
SB bets $1, Hero calls $1, CO raises to $2, SB calls $1, Hero calls $1.

Turn: ($7.50) (3 players)
SB checks, Hero checks, CO bets $3, SB folds, Hero calls $3.

River: ($13.50) (2 players)
Hero checks, CO checks.

Final Pot: $13.50

Results in white below:
Hero has Qd Ac 6c 5s (straight, seven high).
he had [5c 8c 6s 2s] wins with flush
Outcome: CO wins $13.50.

I called the flop looking for a good turn and when he min raised the flop, i highly suspected the straight and figured there was no reason to raise yet. On the turn, i was gonna raise if the other player stayed in, but since he folded, i figured we were likely splitting and he might be freerolling. I could have done something on the river but I didn't have a read on him since it was my first hand at the table. Was this overly passive? If i moved on the turn, I would have lost a lot more.

Well done.

Without a read i'm not prepared to necessarily swallow that he always has the straight on the flop after he bet weakly on TWO streets. A set or even two pair are possibilities, as well as draws, so I'd raise the turn. Against a strong, solid player betting pot on both streets I'd be looking to either fold on the flop (if there looks likely to be a raising war) or play it cagily like you did.