OAuth is crashing my mind

For the platform that makes app-building simple, I cannot for the life of me figure out how to authenticate my Firestore database. There’s no official instructions, the forums assume too much programming knowledge, and youtube videos (that I have tried to find) do not ever address this exact appgyver->oAuth issue.

My Firestore access-without-rules is about to expire, and I’m about to give up. Is there Appgyver OAuth instructions for the person who has never built a secure app in their life?