"아르헨티나에서 축구를 합니다."
Translation:He plays soccer in Argentina.
Theres no way to know the subject of this sentence. I said "They play soccer in Argentina" and it was marked wrong.
It seems "We play football in Argentina" is accepted thanks to many doing flagging!
"They play soccer in Argentina" is also technically correct. However, if there is no apparent subject present in the sentence, you should safely use a singular subject available, because language programs will be more specific about plural forms from my experience with Duolingo and other such language learning programs.