3D FlipBook - htaccess rewrite rule opens viewer file but doesn't start viewer

Here is the link to the viewer: https://landscapearchitect.com/digital-magazine/landscape-architect.php?issue=lasn-december-22.pdf This link works and you can view the pdf.

I am trying to use htaccess rewrite rule to get this: RewriteRule ^emf/(.*) /digital-magazine/landscape-architect.php?issue=$1 [NC,L]

So when I use this link: https://landscapearchitect.com/emf/lasn-december-22.pdf It opens the php, but doesn't start the viewer. It reads the default text in the file: Real 3D Flipbook has lightbox feature - book can be displayed in the same page with lightbox effect.

Click on a book cover to start reading.