I have a scammer that I am chatting to and he told me that if he were to come here (New Zealand), he would first have to travel to South Africa and needed n.z$500 for the "doctor's fee" to get medical clearance.
Does someone from Ghana need to first travel to South Africa to come here?

No, there is a medical clearance, just dollars in US money And the passport is less than 100 dollars

So just clarifying, they don't need medical clearance? But do they need to travel to South Africa first?

No

Yes

When persons you are chatting with starts asking for $$, it's time to block them... end of conversation.