I'm standing right on top of it

IIRC thats the one with the fiends?

You have to go inside the Fiend Ruins and in a building there is a way down and a door opening device to get inside.

he said he is standing right on top of it not outside some place....if your standing on top of it like tha way you said...(if not then explain your self better xD )....go around tha building......its simple maze logic....follow a wall till u get to a goal....in tha case of a maze it may lead to dead ends but your following a wall and will go though dead ends as just part of tha "track"....however in tha case of a building....just go around it..tha other side is trashed and wide open and in tha corner...opposite side of tha wall you aparently standing at if your "right on top of it" is where it is with a sloped floor leading to tha vault 3 door

He also didnt say if his map is zoomed out or not, so if it was zoomed way out being 100 ft away looks like being on top of it

So your attempt of trying to be big headed didnt work Besides the advice I gave him was right, it is infact inside the Fiend Ruins which you must enter into first. So he could have been either outside or inside the ruins he didn't say, so to be safe I said inside the ruins at least if he was he knew he was in the right place, if not then he knew where to go.

@OP your joking lol