Creating a custom login and sign up with React Typescript

Hello, I am currently working on a project where I have to create a log in page using auth0. Since we want to use our own custom page for logging in we have chosen to use the Auth0 api instead. However I am having some troubles setting everything up and getting started. My questions are:

Can I use the auth0.js SDK for this when creating the custom log in and sign up page or will this only allow me to use the auth0 login pages?

Does anyone have a good example of how they possibly used the api in a similar scenario?

As I have understood, everything is done by sending appropriate POST requests to the auth0 api. When it says that I need to use appriopriate endpoints such as /authorize, should this be for example or is it something else?

Is there any good guides with example code of how to call the api appropriately? I have tried using the api docs but its a bit difficult understanding how I should implement it with react typescript.

I sm grateful for any possible help I can receive!

I would like to add that I am currently testing the api and I am having cors errors when trying to send a post request to log in even though I have the right origin url written in my settings.