Didn't have a Sunpass when I passed a toll on 836. Bought a Sunpass afterwards. Can toll be charged retroactive?
More than likely they took a photo of your license tag and will send the bill to whomever the car's registered owner is.
I am not sure, but think 836 is part of MDX, Miami Dade Expressway system which is separate from SunPass, but which does accept SunPass as a form of payment when driving through toll plazas. I think you will need to pay the bill directly to MDX and will not be able to bill SunPass retroactively.