@tuanphan, I solved the problem. I had to embed my Google Slides, I hadn't done that and it worked.
I search under the Help tab in Google Slides, "Publish to web", and then grabbed this embed code:
<iframe src="https://docs.google.com/presentation/d/e/2PACX-1vTZkDz6OqoLl05-SNkQme4nJclDV_5cCenM1bs6IGoqj_VmxQ453tkDoVBgcL4lZcbb9nzPcDBA0Q35/embed?start=false&loop=false&delayms=3000" frameborder="0" width="960" height="569" allowfullscreen="true" mozallowfullscreen="true" webkitallowfullscreen="true"></iframe>
<iframe src="https://docs.google.com/presentation/d/e/2PACX-1vTZkDz6OqoLl05-SNkQme4nJclDV_5cCenM1bs6IGoqj_VmxQ453tkDoVBgcL4lZcbb9nzPcDBA0Q35/embed?start=false&loop=false&delayms=3000" frameborder="0" width="960" height="569" allowfullscreen="true" mozallowfullscreen="true" webkitallowfullscreen="true"></iframe>
You can us Will's Plugin for this,
https://www.will-myers.com/products/p/tabbed-sections
Then you can add the Buy Button from Shopify for each product, individual sections within Squarespace.