Is it obligatory to distribute the amount received from my deceased wife’s death benefit fund according to Islamic law, or should her will be executed by paying the apartment installments from it, knowing that the amount does not cover the annual installments, and is this considered a debt upon her?

The wife's share of the apartment installments is a debt owed by her, which becomes due upon death. It must be paid from her entire estate, and no consideration is given to a will or inheritance except after all rights have been fulfilled. If the mentioned amount is less than the debt, the remaining payment must be completed from the rest of her estate, or the fund amount must be distributed among the heirs after the debt is paid. As for the husband's debts, they are not to be paid from the wife's estate, because a bequest to an heir is not enforceable without the approval of the other heirs.