If you have access to Binance, and you want to withdraw from Coinbase to ioPay, there is a better alternative then going through iotube:
You just withdraw from Coinbase (ERC20) to your IOTX Binance wallet address (ERC20), then from Binance you withdraw to ioPay directly (make sure you input the ioPay address starting from io1, such that Binance understands you want to withdraw to the IoTeX native chain), and you are done: quick and cheap 
If you don’t have access to Binance, then you must do Coinbase->Ethereum Wallet->iotube->ioPay (as WIOTX)->mimo.exchange (unwrap WIOTX to IOTX)