dumb question: "install theme" button missing

Hi everyone, please forgive the stupid newbie question. Hopefully someone will take a sec to help me out.

I’ve purchased a theme on a different site, and I’m following the installation guide right now for WordPress. Except, on step 2 there’s already a problem. Apparently on the Dashboard I should be able to click—

Appearance > Themes > Install Themes

And yet when I do that all I see is the standard pre-fab “Manage themes”, no “Install themes.”

Am I missing something? was I supposed to pay for something else? why can’t I upload the theme I bought?

Thanks in advance!