They must have complied with whatever regulations in order to obtain a "fiat gateway" (which, I presume, means a bank that would give Binance an account)? Binance was seeing a brisk business from 2020 until they were forced to shutter ZAR trading pairs in 2021:

Binance Will Delist All ZAR Trading Pairs on 2021-04-02 https://www.binance.com/en/support/announcement/c04fdd0f33bb462bb53843285a55371f

The central bank's guidance likely helped Binance get back online.

South Africa's Monetary Authority Greenlights Banks to Serve Crypto Clients #60796 https://www.coindesk.com/policy/2022/08/19/south-africas-monetary-authority-greenlights-banks-to-serve-crypto-clients

Here is the regulator's guidelines document:

Guidance Note issued in terms of section 6(5) of the Banks Act 94 of 1990 https://www.resbank.co.za/content/dam/sarb/publications/prudential-authority/pa-deposit-takers/banks-guidance-notes/2022/G10-2022%20-%20Supervisory%20guidelines%20for%20matters%20related%20to%20the%20prevention%20of%20unlawful%20activities.pdf