Create a slideshow from Google Slides.

Either create a Google Slides or import a PowerPoint into Google Slides.

Import your PowerPoint presentation into Google Slides and then click Publish to the Web and generate the HTML code. Copy the code. Google Slides allows you to generate a code that can be embedded into any web page using the source code view. Moreover, you can specify the width and height in order to match your current layout.

On the SquareSpace TCD webpage for the slideshow:

Click the + plus sign on right of the Edit bar, select Code.

in the code Content window paste the Google Sides HTML code.