This is really a losing proposition for you as the tenant/buyer. The list of why "rent to own" is a bad idea is long: steep down payments, high interest rates, high prices, properties in poor condition, etc., etc., etc.
I encourage you to find out why you can't buy, and from there to get yourself in a position where you can. If your obstacle is a down payment, there are programs for that, and "Yes, you must qualify." If income, you need a better paying job. If credit, then roll up your sleeves to ready for the task.