Incorporate the TreeNation Net Zero Website widget in my footer

[AlessandraBest]

Hi everyone, 

I'm trying to incorporate the TreeNation Net Zero Website widget in my footer but I'm not sure how to do it.

It's a widget that measures the emissions of the website and communicates with Tree Nation so that they can offset them; all that one is supposed to do is paste a bit of html code in the footer.liquid.

I've tried following  their instructions

TreeNation Net Zero Website widget in footer

but it's not working. Can someone help?

Here's the link to my shop:

https://57e738.myshopify.com/

password: poolito

Here's the html code I'm supposed to use:

<div id="tree-nation-offset-website"></div>
<script>TreeNationOffsetWebsite({code: '641d957d0d75d', lang: 'it', theme: 'light'}).render('#tree-nation-offset-website');</script>

Many thanks in advance!