HOW? Stream to Mongodb on authenticated users

In the docs, I can only see setting up streams on specific wallets.

What I want to do is to copy the previous setup of Moralis where whenever someone authenticated their wallet on our site, it will automatically fetch all the transaction history of the user’s wallet. But this time I want to push it on my Mongodb.

You can add an address to a stream programmatically, this is the swagger interface
https://api.moralis-streams.com/api-docs/

there are also equivalent functions in JavaScript and Python SDK

You can set up triggers to automatically add an address to a stream once it gets inserted in the db