Adding Google Slides to your signs is an easy way to showcase content you already have created, as well as provide a way to allow others to update the content without modifying anything else on your signs. Once you add Google Slides to your signs, they automatically will update throughout the day if you Google Slides change.
To add Google Slides to you slide, simply click on the Google Apps icon in the slide editor and select Google Slides
Once you select Google Slides, you will see a pop up that asks for the Google Slides Embed Code. You can find the Embed Code by following the steps below:
Go to Google Slides and open the File you would like to add.
At the top click File > Publish to Web
When the popup opens, instead of Link choose Embed and click Publish
Copy the entire embed code that begins with iframe and paste into the box below.
Set the Update Frequency below for how often to refresh the slide content.
For more information about how to publish your Google Doc see here.
Once you insert your Google Slides to your slide, it should automatically update whenever you update your Google Presentation.