Please refer to this topic: https://www.mql5.com/en/forum/40945
Update you meta trader and try it again.
Meta Trader version "Build 778" is the last version.
Your question is complicated between "rent & buy" words.
If you want to rent, click on the rent button, if you want to buy, click on buy button, if buy button is not available, that means said product only for rent, not for sale.