If you exctract the off-line build zip file on a mac the folder structure does not get correct. It seems like the zip file is made in a way, that makes Macs not understand the back slash as a folder slash. Works fine on PC. Never had that issue on a Mac before with other zip files. Do you use a special tool to zip. The screen shot shows how all the files are at the root level on a mac with backslash as just part of the file-name.

The instructions also say "Extract the zip file to the root of an micro SD card.", which is not correct. You should unzip the contents of the zip file's www folder to the SD card's root folder. Otherwise the off-line version will be available on the xxx.xxx.xxx.xxx/www/index.html address