Financing. Rent with option to buy.
This is a classic rent-to-own agreement. Therefore, you don't need to pay a down payment to buy. How does it work?

No down payment.
The price of the apartment is 225.000 american dolars.
If you want to finance the purchase directly with the owner, it's very easy. No down payment is required. For the first three years, you pay monthly rent. This rent is deducted from the price of the apartment. The monthly rent for this rent-to-own option is 1.500 american dolars.. Therefore, you will pay €18,000 american dollars annually, which multiplied by three years is €54,000 amerian dollars., all of which is deducted from the final price. You can move into the apartment immediately.

What happens in the fourth year?
You have paid 72 months of rent-to-own. Now you decide whether you want to keep the apartment or not. In month 73, you must actually purchase the apartment. Up until now, you have been renting it with an option to buy. You will therefore have to pay the remaining price of the apartment. This would be $225,000 - $54.000USD. That is, $171,000 USD.
What happens if you don't pay? Nothing happens, but you will lose the option to buy, and all the money paid up to that point will be considered regular rent. Furthermore, you will have six months to look for another apartment, since the rent-to-own option has been waived.