Sagenlicht, honestly, I think the Open Call is to better versions of those specific maps given as samples on Paizo's page. However, if you already have a city map or other example similar to what they ask, it would work fine.
I think of a "turn-over" map, as here's the publisher's intent, can you as a cartographer create a version that looks more professional? That's their intended goal.
When I said, I was going to do a city map, I was planning on remaking the large city map of their four samples.
But, also, since I posted my portfolio, and I am overworked with my Profantasy commission, I might not participate at all. Especially, since, now I don't need to. As said, though, if I have time, I will try and the big city map is my planned attempt.