Your e-mail confirmation contains a button which says:
If you click on this button you get to see your remain balance and bundles, and you can top-up your bundle online.
When you connect your phone for the first time with our eSIM or SIM card to the network in Indonesia, you will receive a welcome message by Whatsapp. This Whatsapp message contains a link where you can check your balance, or top-up your bundle.
You will also receive a Whatsapp message when 80% of your balance is consumed, and from this message you can also click on a link to do a top up online.
You will also receive a message when your data bundle or your validity period is expired.