The “A” doesn’t go to WTC. Only the “E” ends at the WTC.
You can walk underground from the Chambers St. stop – first to the 2&3 station @ Park Place and then onto the “E” station at WTC.
What I’ve done is gotten out at the Fulton St. Station (make sure you’re at the far west side) and walked a block above ground west to the WTC.
I’ll take your word for it. The map said they are near each other, and my way is still cheaper (which is the sole consideration that was posed). And Shanda about the PATH, huh? They take all that money and build a building no one wants.