These are correct:
It is a five-star hotel.
The hotel has five stars.
When used as an adjective, nouns are normal singular: a ten-minute coffee break, a three-day trek. Most people do NOT say '5 stars hotel'.
How a Chinese startup became a top seller on Amazon.com
Four-year-old Anker is a top seller on Amazon of such products as mobile phone chargers.
After spending several years in the United States, Steven Yang came to the realization that Chinese manufacturers had a great opportunity……