Hi Inma
fdmaxey already answered this extremely well, but it took me ages to write an answer, so I'm giving it anyway:
Yes, outdrew is grammatically as you have already guessed.
In English, you can sometimes use the prefix 'out' to mean to do better than, or exceed. Commonly , you will see it in the verbs like outdo, outmanoeuvre, outflank, outsell, etc etc The sentence that you have quoted is probably using the word metaphorically, not literally.
A draw is something that, for instance, an American cowboy would do - it is the action of pulling a gun from a holster and aiming it at the target.
When fighting a duel, two men would face each other and attempt to be the fastest to draw their gun - because the fastest 'on the draw' would be more likely to shoot first and win the competition. The loser is 'beaten to the draw' or 'outdrawn'.
An example: "The sheriff outdrew the bank robber and shot him dead."