How come his white group in the left wasn’t marked dead by the autoscoring?
In the end he continued to “pass” after “pass”…
I could have put one at A11, but I thought since he pass the server would score that as dead and not as alive?
So I had to put that extra stone?! (when he passed first)
The group was not marked dead, as you thought because it can be still be saved at a11. The scoring system cannot predict your moves and assume wheter or not players are aware of all the weakneses or not 
just do not leave loose ends like that.
That said The scoring system isnt always 100% correct. Thats why both players have to confirm it at the end of the game (you can change status of a group there if you think scoring is wrong)
The proposed score provided at the end of the game needs to be accepted by the players.
The server cannot handle all possible situations correctly. The initial marks are just a starting point. They may be right, but can mis-identify life. The users need to more stones as alive or dead by clicking on them.
In this case, the White group on the left is alive until Black plays A11. Life in this case depends on who is “to play”.