Is Zakat obligatory on a plot of land that was purchased for the purpose of sale, and its full value has been paid, but it has not been actually received due to the incomplete preparation of the مخطط (master plan/layout), especially given the buyer's ordinary financial circumstances?

Since the land was purchased for the purpose of selling it, it is considered a trade asset subject to zakat (definition) if the value of the two partners' share reaches the nisab (definition) (minimum threshold) by itself, or when combined with money or other trade assets, and a hawl (one lunar year) has passed over it. The fact that the partner has not taken possession of it does not negate the obligation of zakat. If he possesses the value of the zakat, he should pay it. Otherwise, it remains a debt upon him that he must pay immediately upon becoming able to do so.