If you want to transfer Crystals from your Surf wallet to the address of a centralized exchange, then you must indicate in the transfer commentary a special text called Memo.
By sending Crystals to the Exchange, you send them to a single recipient account. To transfer Crystals from this account to your exchange account, you need to indicate the Memo in the comment to the transfer.
You can see the Memo text and the transfer address on the website of the Exchange by choosing the option of replenishing the exchange account with Crystals.
Please note that many Exchanges have a minimum transfer amount.
If you forget to enter a Memo or make a mistake with the text, your transfer will remain on the single account of the Exchange. To transfer these funds to your exchange account, contact the support service of the Exchange you need.