16 hours of setting up HeyGen… and I’m still stuck at the beginning 😩

I’ve spent around 16 hours trying to set up HeyGen, and I’m still stuck at the very beginning.

What I need is just a clear step-by-step explanation:
What Files do I need in the end? (claude created like 4 files and I think it is not required)
What Functions do I need? (I have supabase) Or do I even need functions?
What Code do I need?
What do I put in the front end to display the avatars?

That’s it. I don’t need a big project setup or a tutorial on scripting - just the minimal API flow that works.
All I want is a super simple flow: my customer should be able to see a list of avatars, choose one, click “Generate”, and then the video gets created. I already have a script input field and a generate button. The UI part is no problem. The only thing I can’t figure out is how to get the avatars to show up via the API and then connect the generate button so the video is created with the selected avatar.

Every time I try to load the avatars, I get either 401 Missing Header or 500 Internal Server Error. I’ve tried different API keys, checked the docs, and tested a few things - nothing works.