Im visa free but was stopped

You need to convince the immigration officer that you have enough funds and will be able to leave HK by the end of your stay. Bring hotel reservation and onward ticket as bare minimum, and be prepared to show bank account balances and answer questions about current employment. HK immigration has a reputation for scrutinizing travelers from Africa (except South Africa), Southeast Asia (except a few rich countries) and South Asia so your experience is unfortunately quite common.