How to Install Add-Ons in Google Slides
Add-ons allow you to perform additional tasks in Google Slides that you can't do with the basic program functionality. You can add photo libraries, chart and graph generators, additional fonts, and so much more.
You may need to grant access to your Google account.
The add-on is installed and available to use in your presentations.
All of your installed add-ons are available in the Add-ons menu.
The options will vary depending on the type of add-on.