ShopBack Software Engineer, Backend interview questions

First is HR round - 2 HRs interviewed me at their office. Standard questions. Second, they gave me an assignment to work on. During first round, I told them to give later date as I am not free on suggested date but HR told me it won't take more than 2 hours. But it is a long assignment where I need to spend hours and they only gave 2 days to complete. They only allow Nodejs as programming language for coding assignment. So, I am forced to learn that within the amount of time that I have. Another problem is about business problem. From what I feel they are indirectly asking the candidates to work for free in order to solve their problems. They think that candidates have so much free time to work on their assignment.