Can a tenant be forced to purchase rental insurance by apartment owner/manager in order to sign a lease agreement?

I do not know the law , but i doubt it. If the lessee has no interest in protecting his contents and personal liability for actions in his apt or outside of it, then why would he protect your apt from damage or legal liability from his actions in and on the premises or that of his guest? Many actions of tenants extend to other tenants that reflect on your exposure as an owner. I would ask all renters seeking a home in your units if the had an insurance broker / agent that issues a homeowners tenants policy and get his / her name and the policy number. No insurance, then just do not rent. If they cannot afford their own protection, they will ignore your's. Why be a victim of your own negligence and business practices? You do not leave your premises that you offer uninsured. Your insurance does not cover the tenants possessions or liability, but you will have to defend, so why rent?