How did the teachings of Moses the raven create problems for the pigs? What do you believe Moses represents?

Moses taught the animals that there was a place called Sugarcandy Mountain, and said that all the animals would go to it after they died and live in paradise. In Sugarcandy Mountain, the animals would find sugar, clover was always in season, and linseed cake grew on the hedges. Moses was a smooth talker and some of the animals believed in the existence of Sugarcandy Mountain. The pigs had to struggle to convince them it did not really exist.
Although the text doesn't say so, the implication is that by focusing on the dream of a wonderful imaginary paradise after death, the animals were diverted from the task of building a better world for themselves in this life. This creates a problem for the pigs, at least at first, as they want everyone to rally around making Animal Farm the best place it can be and not be lost in dreams.
Moses represents the clergy. He is similar to a priest. Oftentimes priests, who did not labor like common workers, were encouraged by the owners and landlords to encourage people to accept miserable and exploited positions on earth with the promise they would be rewarded after death in heaven. Moses, like a human priest, doesn't work and is the special "pet" of Farmer Jones, and his descriptions of Sugarcandy Mountain sound very much like an animal version of heaven. As the book says:

It [Sugarcandy Mountain] was situated somewhere up in the sky, a little distance beyond the clouds, Moses said. ... The animals hated Moses because he told tales and did no work, but some of them believed in Sugarcandy Mountain, and the pigs had to argue very hard to persuade them that there was no such place.