This is a document that an insurance company provides to the state as additional proof that you have insurance if certain criteria apply to you. An SR-22 form may be necessary if you've had several traffic offenses, DUIs, license suspensions, or driven without insurance. A GU-1338 is necessary if you are a minor wanting to register a vehicle in your own name, or for various commercial use purposes.
Unfortunately, if the DMV has told you that you have to get either an SR-22 or a GU-1338, we can't offer you insurance at this time.