What is the ruling on dealing with Zitouna Bank to purchase an apartment, based on the mentioned procedures, and is this transaction compliant with Islamic Sharia?

The aforementioned transaction can be a Murabaha for the one who orders the purchase, and it is permissible if what transpires between the bank and the client before the bank purchases the apartment is merely a promise and not a binding purchase contract, provided that the bank takes ownership of the apartment and acquires possession of it by vacating it and removing the seller's hand from it.

There must also be a time interval between the bank's purchase of the apartment from the seller and your purchase of it from the bank to ensure the transfer of liability.

It is permissible for the bank to take a sum of money as a guarantee for the client's seriousness, and it is permissible to deduct it as a down payment. There is no harm in Takaful insurance and mortgaging the apartment to the bank until the installments are paid.