Stefan Don't know if it is clear for you from the previous replies, but what they're trying to say ... while there is an IBAN there with the Travel Card membership, and indeed this IBAN is personal, it is only for loading money onto the card. The Travel Card membership doesn't include a bank account in any way. The only way to make payments is use the card as a Mastercard. You can't send money to other bank accounts (except for cashing out the whole amount), you can't use iDeal or Sofort, and direct debits aren't a thing. That's also the reason why you are not able to scan any codes when on the Travel Card membership. There is simply no functionality included that would require scanning a code.
However if you go for a Premium / Pack / Joint membership, you actually get a real bank account that you can do the things with that you are used to from a bank account. Unlimited free SEPA instant payments to any account, handy TransferWise integration for cheap and fast international payments, full iDeal and Sofort support, the ability to pay via direct debit, and you also get a more comprehensive offer of payment cards including not only the Travel Card, but also a Mastercard Debit and a Maestro card that both can also be used with Apple Pay and Google Pay (which the Travel Card doesn't support at this moment). Also you can receive interest on the money in your accounts (but that is imho quite limited, because it is capped at a fixed rather low amount, but it makes everything a bit cheaper).
If that is worth the money, is of course ultimately up to you. If you still have any questions about what you can do with the different memberships, feel free to ask :)