"Kamu mencari koran" means "We are looking for the newspaper," but it can mean, "We are looking for a newspaper."
The man on the newsstand waves his hand and tells you, "Kamu punya koran-koran."
"We are looking for THAT newspaper," makes it clear that we are looking for a particular newspaper. It could be the newspaper of our political party, our city, or our trade association. Perhaps it is the issue that has a story or a photo that we need for an essay.
I entered "Kami menjadi koran itu" which is wrong.
The correct solution doesn't give me any clear insight on my mistake however: "You used the wrong word. Meaning: We are looking for that newspaper."
I'd prefer to see the correct sentence with my mistake highlighted such as "Kami mencari koran itu"