For music.
Do as Polofleece said.
Save it as a .wav file in your sound bank.
The next step depends. If you want it to loop, you need to change the 'main' script in the AI column when it is right clicked. Set it to soundloopinzone. For a sound to just play once, have it as soundinzone.
The sounds MUST be saved as a .wav, and in your soundbank to work.
The sound will ONLY play in the sound zone you placed it in so just make the zone bigger, if you want to have it over a certain area.
As for the enemies,
Spawn your enemy, name it say (Ambush01) - You can do this with multiple enemies for more enemies, they can all have the same name.
Now, create a trigger zone. Change the AI - Main script to 'plrinzoneactivateused'
Now in the column, where it says, If Used, paste the name of your enemy, in this case Ambush01
That should all work.
TiTaniUm