Is it permissible to take a loan for finishing an apartment from banks that claim their dealings are in accordance with Islamic Sharia, in order to expedite marriage?

If the transaction between you and the bank is conducted according to the Sharia-compliant regulations for transactions, then there is no harm in dealing with it due to your need for it. However, if the bank does not adhere to Sharia regulations in its transactions, then it is not permissible to engage with it in a forbidden usurious transaction.