Yes, you may! Add your card to Apple or Google Wallet and use the nearest ATM that supports Apple/Google Pay to make withdrawals. You may use your physical card in an ATM also.
A PIN is required for ATM withdrawals, so make sure you create or update your card PIN on the ‘Home’ screen in the app. See here how to set up your card PIN.
If you’re withdrawing foreign cash from an ATM outside the US, please be aware that most ATMs will give you the option to use their own rate of conversion (this usually has a fee higher than the official mid-market rate) or use the rate of conversion of your financial institution (GrabrFi in this case). If you use GrabrFi's rate of conversion, you’ll receive local currency at the official mid-market rate.
Please remember that you will be able to withdraw the local currency of the country where you are withdrawing cash from.