Do I need Client Cert and Pass? If yes, how to obtain those from Azure AD?
Should I use OAuth2 method for authentication? If yes, how to obtain Access Token from Azure AD?
Another authentication options are: None, Simple HTTP with username and password, OAuth1.
In Azure AD I already have an app registration with required permissions (Microsoft Graph) which I use for connection to Excel 365. Can I modify it for using with Sharepoint either? Here is Azure AD app registration screenshot.