€4 NL HE STT: Lost my whole stack straight over straight on the river

It was the second hand of a 5-player S&G,

SB: 51 BB
Me (BB): 50 BB
UTG: 50 BB
CO: 50 BB
BTN: 49 BB

Pre-flop:
SB posted 0.5 BB
I posted 1 BB
3 players folded
SB called
I checked

Flop (2 BB): Jc 9d 7s
2 players checked

Turn (2 BB): 8s
SB bet 1 BB
I called

River (4 BB): Th
SB shoved 49 BB
I called
Uncalled bet 1 BB returned to SB

Showdown (100 BB)
SB showed Qd 8h ([Qd] Jc Th 9d 8s, straight, queen-high)
I showed 6h 3c (Jc Th 9d 8s 7s, straight, jack-high)
SB won 100 BB
I was busted

Where did I go wrong? I called at the turn with an open-ended straight draw, so I could win big when it hit. It hit, but I ended up losing the whole stack.

Sorry, I just found out I was a complete idiot. The board itself already contained a straight!

Preflop
In theory you can attack SB limps with garbage, but 63o is so bad, that I would definitely also take a free flop.

Flop
Again you could stab when checked to, but you have a really bad hand with two undercards to the board and no draw. So I would pretty much be in check and give up mode here. We should bluff a lot blind vs. blind, but its nice to do it, when we have at least some equity, and its always ok to give up with our worst hands.

Turn
You have 8 outs to a straight now, but a T will put the straight on the board, which mean, you are still only chopping the pot at best. So in reality you only have 4 outs to a 5. And even then you will still lose to any hand with a T in it, which has a better straight already. So this is a pretty extreme example of, what we call a "bad draw", where making your hand will often just lose you more. And for that reason you should fold.

River
Yeah you said it yourself. You are playing the board, so its a complete disaster to call a massive overbet. See it as a learning experience and take in the point, I made about turn play, and avoid chasing after bad draws.