You will not be asked to provide IBAN details during the Blocked Account activation since Expatrio will open a free Bank Account* automatically for you during the activation. You can read more about the Bank Account here.
If you choose to open a bank account with a different provider, please make sure that your bank account is activated and ready to receive funds before you activate the blocked account, otherwise your bank will return the transfer and you will get your funds with a delay.
You can find useful information and account set up tips for the banking providers we recommend here (including how to open a German bank account product* via Expatrio!), but you do not have to choose from this list. If you already have a SEPA account (for example a German bank account) set up in your name, you can use it for Blocked Account activation.
* Banking services are provided by our partner Aion Bank