You shouldn't need to extract any files, or unzip them. Just copy them to an SD card and insert them in the camera/ST-16 depending on what you're upgrading.
ok,,, here's what I had to do... The st16 did not recognize the zip file. I had to rename the file to .yuneec for the st16.. The file for the H had to be renamed to .bin ... Both files downloaded as .zip and could not be extracted and were not recognized so the drag and drop doesn't work if this is the case for some it looks like.
They should not be ZIP files. They are BIN files. Rename the extension to BIN instead of ZIP and just transfer the files to the micro SD card and put the card in the camera.
Some browsers rename BIN files to ZIP when they download.
I had the same problem when I updated. I had to rename the H file from .zip to .bin and ST16 file from .zip to .yuneec. Updated like a champ then. Had not read that anywhere.