Test SSO without an CAS or OAUTH2 Server

You have to change this file: /admin/tool/mobile/launch.php

Just comment out Line 63 like this:

if (empty($SESSION->justloggedin) and
        $typeoflogin != tool_mobile\api::LOGIN_VIA_BROWSER and
        $typeoflogin != tool_mobile\api::LOGIN_VIA_EMBEDDED_BROWSER) {
    // throw new moodle_exception('pluginnotenabledorconfigured', 'tool_mobile');
}