You CAN NOT set up a direct debit on your blocked account, which means you can not use your blocked account to pay for your expenses. Moreover, please don't provide your blocked account details (IBAN, BIC) to your service providers, as their direct debit requests will be declined.
You can pay your expenses, or set up direct debits from a current account (a regular bank account) that you can open in any bank that operates in the EU SEPA area and provides you with an IBAN. By setting up monthly payouts in your Fintiba app, you can transfer money from your blocked account to such a current account, and use it to pay for your expenses.
☝ Important: Please ensure that the bank where you plan to open a current account accepts the "SEPA Mandate" for the monthly payouts from your blocked account.