All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
What we understand from your question is that this organization lends the buyer the cost of the house and then he repays the amount by installments with an interest. So if this is the case, then this is forbidden, because it is Ribaa (interest and usury) which Allaah and His Prophet have forbidden. This is something which is absolutely known in religion with evidences and no one can deny it. There are many evidences about this, but will not be discussed here. Some of these evidences are mentioned in Fataawa: 81346 and 82049.
Saying "sale to lease" and "repayment of lease" could be understood that the transaction is rent which ends up with owning the property. This is also forbidden as it is two contracts on one particular thing. This is not permissible in Islaamic jurisprudence. This is previously discussed in Fatwa: 81863.
For this transaction to be correct and permissible, it could be as follows: The buyer should ask the organization to buy the house on the agreement that he will buy it from them with a specific benefit. So when they buy the house and it becomes under their possession and under their guarantee, then they sells it again to the buyer. This kind of transaction is discussed in details in Fatwa: 87956.
Allaah knows best.