The exchange that you are transferring from may show your transaction as completed, which may mean that the exchange has successfully added your transaction to the blockchain. It does not mean that your funds have cleared in your Wealth99 account.
Once your transaction has been added to the blockchain it can take some time for the process to complete. This is because different blockchains can require a varying amount of confirmations to verify the transaction.
You can use your Transaction ID to follow the transaction's status on the blockchain. See how to find your Transaction ID.