Embedded script working only in Safe Preview and not when saved.

Hey, I am doing a site for an artist and I need to insert a codeblock to make an image of one of his painting which is 200mt long display on the website. 

I made a code that displays the image and a script that auto-scrolls it from the left to right and behind.

The code works on my machine, even on the "Safe preview" in Squarespace, but when I save, nothing works like expected, the image is just still and on the left.

I have tried injecting the script in the header of the page, but still didn't manage to make it work.

Can anyone help me figure out what is the problem, and why it doesn't work when I save?

Can you share link to page where you added it? We can check easier