Step 1.
Create your animated slideshow at powtoon.com. Use one of the free templates unless you can pay for the app (avoid any templates that are Pro or Pro+
Step 2.
From the My Powtoons dashboard, click on the Export icon.
Step 3.
There's lots of export options. Choose Embed. On the next screen, add any details, and choose a category, then click Next. Then, click Share Powtoon. Finally, choose your size and copy the embed code.
Step 4.
Import into Book Creator and you'll get something like this.
