Is it permissible to use money from salaries received for months in which no work was performed, to open an account with Aramex and purchase goods from Amazon, then recover the spent amount after selling the goods?

The basic principle is that this money is not permissible for you. You must return it to the responsible authority or inform them of the matter. If they permit you to benefit from it, then there is no harm; otherwise, not. This is based on the Prophet's (peace and blessings be upon him) saying: "On the hand is what it took until it returns it," and "Whoever has wronged his brother concerning his honor or anything else, let him seek his forgiveness today before there is no dinar or dirham."