We have an external application that makes REST calls to SharePoint on-premises using basic authentication (user and password). This SharePoint have been recently moved to SharePoint Online and since then the REST calls returns Forbidden 403.
I think we need to switch to Oauth2 to keep making requests but I am not totally sure if this is the case and if so how can we register our application in SharePoint and which fields we need to add to our API calls (Client Id, Client Secret...).
How can we keep using our external REST API calls to SharePoint online?
