Anytime you are sending ETH or an ERC20 token, there must be a sufficient balance of Ethereum (ETH) in your wallet to cover the cost of gas (another name for transaction fees). If you do not have enough ETH to cover this cost, you will not be able to send the asset. Instead, a message of an "insufficient balance" will appear:
If you need to purchase some ETH, you can do so directly in our app via Banxa. Instructions on how to do so can be found here.