Apaullo

Apaullo is a metaphor for the United States of America (Cold War Allegory Theory)
If the theory that this film is an allegory for the Cold War is to be believed, then Apaullo would most certainly be the metaphor for the United States of America. He is the embodiment of how Russians see Americans, greedy capitalists. This would absolutely play into the idea that this film is Russian propaganda, attempting to portray America as evil and villainous.

Apaullo is a Spirit
Apaullo is seen using supernatural powers throughout the film "The Myth of the Money Tree" (Namely, Apaullo's use of telekinesis on an office chair and the forced-teleportation of Sibcy from the 6th floor to the ground floor of the office building). This, combined with the fact that there are several logical flaws with their so-called "company" (hinting that it's not real), suggests that they are not human, but some kind of supernatural being.

River Magnus vs. Apaullo Theory
It is speculated that the two deities, River Magnus and Apaullo, are locked in an eternal battle of ideologies. River Magnus represents whimsical freedom and Apaullo represents grim pragmatism, which will ultimately result in a final battle on a cosmic scale.

Trivia

 * Apaullo's name is strikingly similar to that of Apollo, the Greek/Roman god of the sun and light, music and poetry, healing and plagues, prophecy and knowledge, order and beauty, archery and agriculture. He is also said to be harmony, reason and moderation personified. This may explain why Apaullo is the character with the most practical and reasonable ideology in the film "The Myth of the Money Tree".
 * Apaullo wears eye makeup that is likely inspired by Egyptian eye makeup, possibly linking them to the sun god Horus / Ra, considering they are named after the sun god, Apollo.
 * Thomas Streed, the director of the River Magnus films, is seen referring to a scene as taking place in a "dreamscape" - this may actually hint the entire setting of the film taking place in purgatory / some kind of dream realm.