3D FlipBook - Crash during zoom in Iphone Safari

I bought the plugin and when I try it out on my server using Safari on Iphone, it seems to crash when I zoom in and out by pinching quickly. It says "A problem repeatedly occurred on http://......."

Here is my site: http://ftp.directprinting.com.hk/nippon2/3dflipbook/index.html

Here is a video of when that happens: https://www.dropbox.com/s/hj98hzh900tx36q/RPReplay_Final1602937759.MP4?dl=0

Thank you.