Internal Server Error

I just tested that file on my website and it works fine!

Where do you see the error? Where the pdf should be?

Try this shortcode instead:
[pdfjs-viewer url=”https://treymag.com/wp-content/uploads/2016/08/mag.pdf” viewer_width=100% viewer_height=1360px fullscreen=true download=true print=true]

ok let me try this short code

See this URL:

https://treymag.com/1623-2/

I used the above short code

Make sure you don’t have any security plugins preventing the PDF from being loaded.

You probably have a .htaccess rule preventing access to the PDF.
See https://support.hostgator.com/articles/how-to-edit-your-htaccess-file
And make sure you don’t have special access rules for wp-uploads