DayBack Online requires your data be hosted on FileMaker Server 12 or higher with XML web publishing enabled and php running (the php that comes with FileMaker Server works great). You'll also need to have access to place a simple php file on your FileMaker server.
You can run DayBack Online inside your FileMaker Go solution (or inside your Pro solution) by placing it in a webviewer: this is the same thing you'd do for WebDirect and you'll find details here.
You can also just open DayBack Online in Safari on your iPad, even configuring custom actions to then open records in your FileMaker Go file as needed. DayBack Online does require an internet connection, however, as it does not have an offline mode.
DayBack Online works great in WebDirect from FileMaker Server 14 and feel very fast. (We haven't tested earlier versions of WebDirect and can't support them). More here: WebDirect.