Before you spend hours over hours figuring out what file this is, from what server it is actually served, what configuration must be done to make this work: Can't you just simply download it via FTP? Just asking, because web servers are just not made to deliver "pages" or other resources like files that are so extremely big.
Else, if you absolutely want your web server to deliver very large files, you will need to check Google for all the directives that this needs. There can be issues in PHP, in Apache and in Nginx. It can be issues with the maximum allowed block size, maximum allowed file size, the RAM that this operation needs, the timeout values in PHP (e.g. the script run time must not expire before a script has completed content delivery) etc. Simply walk through all parts involved to find a solution. I doubt that it will be possible to go through all these different aspects online in a forum.