I'm looking for a short story
"Hunting Problem" by Robert Sheckley. You can read it at the Internet Archive; note that pages 29 and 39 are transposed in that scanned copy of Galaxy Science Fiction.
about an alien who, in order to be accepted in some kind of "space patrol", needs to prove his worth by bringing the skin of a human using only traditional methods of hunt. The alien race don't believe humans are intelligent beings, also, they don't use the word "human".
They call the humans Mirash:
The Leader studied him for a moment. Then he said slowly, "Drog, how would you like one last chance to make first class, and win an achievement badge as well?"
"I'd do anything!" Drog cried.
"Very well," the Patrol Leader said. "What is the name of our patrol."
"The Charging Mirash Patrol."
"And what is a Mirash?"
"A large and ferocious animal," Drog answered promptly. "Once they inhabited large parts of Elbonai, and our ancestors fought many savage battles with them. Now they are extinct."
"Not quite," the Leader said. "A scouter was exploring the woods five hundred miles north of here, coordinates S-233 by 482-W, and he came upon a pride of three Mirash, all bulls, and therefore huntable. I want you, Drog, to track them down, to stalk them, using Forest and Mountain Lore. Then, utilizing only pioneering tools and methods, I want you to bring back the pelt of one Mirash. Do you think you can do it?"
The alien found three dudes (I think some sort of criminals in a clandestine quest in a swamp or something like that) and, after many attempts, he finally succeeds . . . But at the end, what aliens believe is human skin, is actually only the clothes.
The Scouter Jamboree was a glorious spectacle. The Soaring Falcon Patrol, number 22, gave a short pantomime showing the clearing of the land on Elbonai. The Brave Bisons, number 31, were in full pioneer dress.
And at the head of Patrol 19, the Charging Mirash Patrol, was Drog, a first-class Scouter now, wearing a glittering achievement badge. He was carrying the Patrol flag—the position of honor—and everyone cheered to see it.
Because waving proudly from the flagpole was the firm, fine-textured, characteristic skin of an adult Mirash, its zippers, tubes, gauges, buttons and holsters flashing merrily in the sunshine.