Error "This video cannot be used as template" and "This video doesn't support template.generate"

I am using Zapier to connect to HeyGen. I am trying to use the "Create a Video From Template" but I get the "This video cannot be used as a template" when I try to use the video ID of a completed video. If I try to use a Template Video ID, I get the "This video doesn't support template.generate" error.

I've followed the documentation, blog, and live webinar but still can't get it to work. What should I do?