Judging from what I see online, Standard Theme is a WordPress theme. You’d install it into an existing WordPress installation — it wouldn’t be usable on its own.
If you’re new with WordPress, I’d strongly urge you to check out other available WordPress themes before going with this one. $100 is a lot to drop on a theme, especially when there are literally thousands of excellent free themes available on WordPress’s site:
If you’re sure it’s what you need, though, then go for it, I guess!