You probably shouldn’t have told him that Rachio has a mobile app. Just have him visit app.rach.io in Chrome (Android) or Safari (iOS). It’s very straightforward and ad free. Unless you are using one of the features that doesn’t appear on the website, you may also find the web more convenient, because it works the same as in Windows, Mac or Linux. In your mobile, you can save the site to your home screen and think of it as the ‘app’.