How to create OAuth client app and flow for website intending to integrate Sharepoint data

Question

I'm building a web app that intends to provide insights and analysis on user's Sharepoint and OneDrive data. Users should be able to come to my web app, connect their Sharepoint and OneDrive data by going through some oauth flow and agreeing to 'read' scopes we want on their workspace data, and then we should be able to generate an access and refresh token on their behalf for usage in our app according to the scopes they agreed to. For example we want to be able to search over a user's sharepoint data given some input query.

It's unclear to me, what guide should I be following? One of these or some other guide?

• https://learn.microsoft.com/en-us/azure/active-directory-b2c/authorization-code-flow#2-get-an-access-token
• https://learn.microsoft.com/en-us/azure/active-directory-b2c/openid-connect#get-a-token