What is the ruling on paying 5000 dollars as an advance rent for two apartments for a period of 6 months, and handing them over to a company that rents them out monthly at a higher price, with the capital and half of the profit being recovered immediately upon the apartments being rented out?

The basic ruling is that it is permissible to sublease a rented property if the second tenant is similar to the first in terms of usage or uses it less intensely. There is no objection to your friend acting as a broker and receiving a commission (ju'alah) in exchange for a percentage of the profit. So, if you rent the two apartments, it is permissible to give them to someone who will lease them to a third party, on condition that this intermediary receives half of the profit. This is a type of brokerage and mediation in exchange for a percentage of the return. The evidence for this is the saying of the Prophet, peace and blessings be upon him: "Muslims are bound by their stipulations."