In addition to Ted’s comments, I would also review a copy of the agreement you have with the property management company. Does the agreement give them the right to sell the property on a lease purchase? (This would be highly irregular.) Does PM contract transfer with the sale of the property like a lease? (Also highly irregular.) In my experience in property management, they do not have the right to negotiate and accept a lease purchase without the written consent of the owner.
That’s a tricky situation. You might want to ask a local real estate attorney. Purchases are subject to existing leases, but if the lease was renewed/modified between the time you had an accepted sales contract and the actual closing, at a minimum you did not receive the property in the same status it was when you wrote the sales contract. If it were me, I’d be taking my sales contract and the prior lease (which you should have gotten a copy of) to an attorney for a quick (and hopefully free or reasonably priced) consultation.