Almost all exchanges require a Memo ID (XLM) or a Deposit Tag (XRP) for transactions to successfully be deposited to your account, if you did not include this on the withdrawal, you will have to contact your exchange to see if they can recover your coins. They will need the Transaction ID, this is sometimes called "Payment ID", "Transaction Hash", "TX:ID" or something similar, you can find it in your Celsius app withdrawal history.
Example of an XLM transaction without a Memo ID:
Example of an XLM transaction with a Memo ID:
Example of an XRP transaction without a Deposit Tag:
Example of an XRP transaction with a Deposit Tag: