Thank you for your help, Paul.
I am not much of a wordpress expert. The login button is just an HTML code with a link to go to https://mysite.com/wp-login.php?external=oauth2&id=1
Are you saying to use wp_login_url( get_permalink() ); with the “/wp-login.php?external=oauth2&id=1” part at the end of the code in the HTML?