In most cases, if a design will not download it is due to the file size being too large.
Larger graphics or videos will make the file size too large to download.
Too many pages with a lot of graphics, videos and text will also cause download issues.
Try downloading only 1 page of the design to see if that works. If it does, that means the file size is too large.
You may try splitting the menu pages into more than one design to download each page separately. Make a copy of the menu, then delete pages from the copy.
Other download issues could relate to cache/cookies in the web browser or slow internet connection.