Claude only gives me HTML for my social media carousel

Inspired by this guy, I thought I'd use Claude to create my social media content. The carousel is cool enough, but I only get an HTML file where I would rather have a WhatsApp/InstaGram friendly format. Been trying to find a way to convert to MP4 but it is surprisingly complicated. I either have to manually screen record the carousel or use some rather complicated workarounds. I kinda managed with Puppeteer, but it takes a lot of tweaking of values and testing to get it right, meaning it's a fking hassle and I need to tweak the values again for carousels with different lengths.

Meanwhile, my friend says she got MP4 directly from Claude. My Claude claims it can't do that. How can I fix this? Is there another tool I can use? It's just a hobby project so I'd prefer to keep costs to a minimum.