The 23-year-old Dutch international was signed from AZ Alkmaar in August and he credited his countryman for persuading him into signing for La Dea.
“He told me about many things about the club, the players and the coach,” Koopmeiners said on the official club website.
“But he also spoke to me about the city and the country, he immediately made me feel welcome. I also started taking Italian lessons.
“I like how the team play. I think they are the right club for me. The way they attack, the way they play the game. I also really like the squad and the players, so I’m really excited. Then I liked the city a lot.”
Koopmeiners also gave Atalanta fans a brief description of the type of player he is and how he likes to function.
“[I am] a midfielder who likes attacking football,” he said. “I like to help my team and also defensively I want to work hard.”