How do I know if a company is a scam?

Received a job offer from a local startup (currently only the owner itself leading the team) and I am the first hire. I applied through jobstreet. When I interviewed for the position, there were three Malaysian Chinese that interviewed me, which claimed to be the boss’ employees from another business. Webcam was not on the entire time.

I’m currently unemployed so I decided to take up the offer. The pay is pretty decent. When I looked up the company’s name on SSM it is showing the business was established 20 years ago and is currently dormant. My dad said that people like to just acquire a dormant business for a startup, so idk. My question is, would scammer take a lot of efforts and go so far to get someone sign a job offer, then work for free? I have already signed the offer, but still feelin a bit sus tbh, it just doesn’t feel much right to me, but good thing is I get to work from home the first two weeks.