Did you keep it in park the whole time? I tried this with my 2016 Accord and got bored so went for a drive and in the middle of said drive the update failed. Never tried after that.I received my 32GB USB drive. I followed the instructions above and the update process was straightforward. The maps were updated from version 2018.10 to 2019.11.
The USB drive I ordered is the SanDisk Ultra CZ48 32GB USB 3.0 Flash Drive