Is it permissible to borrow from the owner of a company that deals with the institution where the questioner works to buy land and build a house on it, knowing that their relationship is purely fraternal, and the company owner does not ask for any help in return?

A حسن (goodly) loan is a virtuous act, encouraged by Islamic law, as it relieves a Muslim's distress. If your work at the company is merely typing and formatting administrative letters, without you having any decision-making power to bring benefit or repel harm from the institution's owner, and the lender does not intend to influence you, then there is no objection to you accepting the loan. However, if the lender intends to win you over to overlook his mistakes, then it is not permissible for you to borrow from him, because it would be usury (riba) on his part and a bribe on your part. If his intention is merely to help, then there is no objection, and consult your heart.