Hello. The available fonts you see there are so called web fonts, meaning they are almost always available on most user computers be it Windows or macOS or Linux. By users I mean web visitors who are going to see your published project. Additional fonts is something that is usually managed by a website page that loads the viewer. Your web designer & developer decide what fonts to load when user lands on a web page.
So you can confirm with your web developer the font you need to load (so they include it on the page) and then enter the font name in the font field drop-down on the Hotspot form.
