After "mix phx.gen.auth Admins Admin admins" with added working register and login path.

lib/beet_round_server_web/controllers/admin_session_html.ex

@@ -0,0 +1,9 @@
+defmodule BeetRoundServerWeb.AdminSessionHTML do
+  use BeetRoundServerWeb, :html
+
+  embed_templates "admin_session_html/*"
+
+  defp local_mail_adapter? do
+    Application.get_env(:beet_round_server, BeetRoundServer.Mailer)[:adapter] == Swoosh.Adapters.Local
+  end
+end