It would appear that you are being required to obtain a SR-22 to reinstate your license in Ohio but do not own a car. For this type of situation you would need a non-owners SR22.
There is a form known as a SR-24 that we are aware of but the SR24 was originally designed to be a notice of change of motor vehicle in regards to a car listed on a policy with a SR-22. In recent years the use of the SR24 has almost disappeared. When notification of a change of vehicle is required by the state, a replacement SR22 is generally utilized.
If you are not required to maintain a SR-22 but need to have insurance to acquire an Ohio driver's license then you should get a non-owners policy since you do not own or intend to purchase a vehicle in the near future.
If there is a different SR24 form that you are referring and need information on contact the OH Bureau of Motor Vehicles (BMV) and/or the OH Department of Insurance.