How to make a post request in firebase

Hi guys
I’m making a game app in which users’ answers need to be stored in a database. I’ve tried methods like jsonbox and restdb.io, but I can never get it to work. The last attempt is firebase, I already created a project and already made ‘Get’ work, but ‘Post’ does not work. I can’t find anywhere to talk about how to integrate the post in appgyver, only get. Can you help me?

https://docs.appgyver.com/appgyver-academy/tutorials/tutorial-articles/google-firestore-rest-api-integration

make sure your security roles allow posting

So, I followed everything according to the step by step, yet when I do a test it shows this error screen. I don’t even know if the problem is in the appgyver, maybe it’s something in firebase, I don’t know.