It's not React only. It has pure/regular HTML, React, and Vue. I have mainly only used the pure HTML personally as I use Phoenix/LiveView for most of my stuff, and it works phenomenally well and is very copy/paste friendly. The UI/console they provide is also top notch. For others who do use React, the React stuff also worked well too for one project I did that was a SPA.
It's well worth the money IMHO.
I just had a more-detailed look, and I'm not sure where I'd find the pure-HTML stuff? From https://tailwindcss.com/plus/templates/pocket#pricing:
"Our website templates are built using Next.js, so all of the markup is written using React"
And the individual components that make up these templates don't seem to have pricing attached, nor non-React usage examples?