You can't transfer directly from CEX to Emerald/Sapphire. First you need to send to the web wallet as web and extension wallets are native so they can withdraw and deposit to CEX. From there you can send funds to your Metamask wallet to use on emerald. Or you can bridge directly into Metamask from other networks, but as we saw earlier, not all pairs are supported. You can follow the steps from this tutorial: https://docs.oasis.io/general/manage-tokens/how-to-transfer-rose-into-paratime/