Isn't a moon unlikely to happen in this kind of planet?

The planet itself may not have a strong eletromagnetic field to maintain a moon. Maybe some asteroid.

Not only the sun, but the planet's temperature may be it's "north". I mean, hot places, like the center of the ring, would be the "north", and the cold places may be the "south".

The world may be next to some medieval versions, like the flat pizza world, with the "end of the world" as waterfalls to "nothing". In this planet, the hot and the frozen places might be the "end of the world".