You're sort of right about exit A, but walking along 3rd Ring is the least desirable way to play it. Basically, going through the mall (all the way to the north doors) is my preference; the Ren is just across the small street.

My second choice would be to exit the mall on the west side and walk north on that street/path.

As you approach exit A from inside the subway station, there are a few sub-exits that put you inside the mall; just look for the signs: Viva or 富力广场. If you happen to miss those, it's not the end of the world; you'll have no trouble figuring out how to go north.