Not sure what the exact ordinance is they fall under here.
I have seen them go up on outside storage container on the zoning board of adjustment.
Most are approved, but for cases like above. usually as storage is needed for a construction project. I can not say I have ever seen one on the agenda as a resident just wanting one for an indoor storage area.
If I was doing it, I would be very careful about what I said it actually was. Different names and uses, have different rules.
If I had to guess, would have to be something temporary and not permanent. Temporary would just give you a period of time to keep it there, and then it is removed.
Permanent storage structure might have other codes you need to meet. Something of that size may require a concrete slab. I know there is a limit to size of sheds, before even a permit is needed. I think here is is 120 SF.
Having said all of that, the truth is you may or may not get by with just doing it. Zoning inspectors on the street are so busy they really do not have time to seek out items such as these.
Unless, they get a complaint about it. It may not even be a complaint it could be the inspecting the garage build next door to you. It could be the addition across the street, a pool, or any number of things, that a city official could just see it while conducting business close.
Keep in mind there may or may not be anything about a storage container in that language. Call it what you want, and that may satisfy zoning. It may still not pass building codes.
Carports here are the best example of that. They are mounted permanently, but many are not on a slab, and many are to close to something that would require them to have a firewall. Putting a wall in one would never meet code, and making an existing garage or house wall into a fire rated wall just is not economical.