Your funds can be deposited into your eWallet as soon as V.Group registers your account. However, to gain full control over your funds and manage them according to your preferences, you must create a ShipMoney account and register your card online.
The ShipMoney app is a low-data-usage application, like other online banking apps. It uses less than 1% of your onboard data allowance and should not significantly impact your overall data consumption.