Users need to have and account at Binance. Or register one.
Once account set and passed the KYC requirements (needed to enable withdrawals), users just need to deposit the amount of USDT/BUSD they want to convert to Bep20 to their Binance account wallet.
After deposit is confirmed, the transferred USDT/BUSD amount will appear in the user Binance wallet. On the Withdraw section of the Binance App, users can just withdraw to a Bep20 external wallet of their choice by selecting the respective transfer network, Binance Smart Chain (BSC) in this case. Same applies for BUSD. Withdrawal fees are very low, usually just a few cents.
That's it! Erc20 converted easily to Bep20 and users can purchase RGP with minimal fees: https://buy.rigelprotocol.com/buyRGP
Full info about KYC verification at Binance: https://www.binance.com/en/support/articles/360027287111-How-to-Complete-Identity-Verification