David, on windows you'll be setting up cron using scheduled tasks, you can refer to moodle documentation about setting up cron jobs in windows HERE.
where running moodle through browser is concerned, newer moodle have a default setting to prevent running of cron via browser/url, that is why you're seeing this message of disabled by administrator. for that go to site administration > advanced features > site security settings > and find yourself to check box, cron execution via command line only (as shown below), uncheck it and you wont see that error.
