Non-owners auto insurance is for drivers who do not have a vehicle but need to file an sr22.
If your driver license is suspended for no insurance tickets, driving under the influence or for any other reason and you do not own a vehicle you will need a non-owners policy.
A non-owners policy is a state minimum liability auto insurance policy.
It would cover you in any vehicle you drive, but is purchased to satisfy the sr22 filing requirement for drivers with a suspended license.
Source
Licensed agent