Add a new content block to your site. When adding your content block – choose “Embed” 

When the embed window pops up click on the </> icon at the right hand side of the input field – this enables the more advanced embedding which we need for the widget

This opens a further pop-up window into which you can paste the full embed code – we need both the anchor tag beginning <a href and the <script> tag which follows to enable the widget.

Click set and this window will disappear and you will see a new embedded scripts block with a large button that says “Preview in safe mode”

Clicking this button will display widget in your preview.

Finally, click apply in the embed widget window to apply the changes.