Fathom sometimes does not start when I start a Zoom call -no way to control it

I have a Zoom account and Fathom apparently comes with it. I want Fathom to automatically start recording on all of my Zoom meetings - It automatically starts on some of them, but most of the time when I start a Zoom, Fathom does not. In those cases I want to turn Fathom on for video recording and transcription  but there is no means of doing so. When I am in the non-Fathom meeting and I click on the "Apps" button at the bottom of the page, "Fathom" does not appear. It is a complete mystery to me why Fathom starts sometimes when I start a scheduled meeting, and sometimes does not. So if I can default to it automatically starting in every call, I can turn it off when needed. What's the secret? Why's it hard to find? I don't even know if I'm on the right board.