Add font button in iPad Illustrator not showing up

I'm trying to add downloaded TTF files into Illustrator on the iPad. Everything I have seen online shows that the add font button should show up under the properties tab next to "Your Fonts" when selecting a font. However, the add font button isn't showing up for me. The rest of the window appears as normal, but that one button is missing. Does anyone have any tips for how to troubleshoot?