Help! I don’t own a car but need insurance

Cardholders often assume that credit card car rental insurance will cover them for damages to third parties (people or property). In fact, Collision Damage Insurance (CDW) or Collision/Loss Damage Insurance (CLDI) offered by credit cards only covers the rented vehicle. In addition, CDW and CLDI do not cover losses to property stolen from the rented vehicle itself. While third party liability coverage is not offered on credit cards, some credit cards do offer Car Rental Personal Effects Insurance. Personal Effects covers theft or damage to items belonging to the Cardholder if the item is stolen or damaged during the rental period.

See article here