https://our.umbraco.com/forum/using-umbraco-and-getting-started/114076-understanding-umbraco-13-auto-linking Summarizing from a post I made on the forums at the beginning of the month: I was trying to set up a custom login process (not oauth/openid) for a company and was running into issues getting it to actually create / autolink a Member after verifying the request. https://github.com/ChristopherBass/UmbracoThirdPartyAuthTest/tree/main I say "was" because in the ensuing month I've since given up and just have the Controller do the authentication redirects / response handling directly and manually signing them into Umbraco using IMemberSignInManager, but I'd still like to know what the right way was, for the future.