Am I sinful for organizing company papers for a government entity on behalf of a Saudi employee who does not show up for work, and for signing on his behalf using a stamp bearing his signature, and what should I do?

This action falls under the category of "thaman al-jah" (the price of influence), which means that a person expends their influence or power to help another obtain their right. Scholars have differed regarding the ruling on taking compensation for it, and the preponderant opinion is that it is permissible to take the equivalent wage (ajr al-mithl) if the person of influence expends expense or effort in their endeavor; otherwise, it is not permissible. The solution is for the company to assign this person some work in exchange for the salary; otherwise, the salary is not permissible for him.