KAYAK Junior front end software engineer interview questions

I received a take home test that took me 3-4 hours to complete, and finished it before the due date. I emailed them back my work and I was expecting to at least get a reply, a rejection or a request to schedule, something. Nope, they completely ghosted me and it’s been a month now. Are they just getting people to do free work for them? This is unacceptable and very unprofessional. If you are a junior engineer, I’d avoid this company if you don’t want your time and effort wasted.