Depends what you want to do with it. If you are looking to start using a virtual training platform such as Zwift from your computer, then you need an Ant+ dongle compatible with that computer (they are about a tenner) and you can install the training software and then pair the trainer up with the app. It looks like it already reports power output so you can use it immediately without a cadence sensor.
It doesn't let the app control the trainer though so you wouldn't be able to take full advantage of the features of the training apps.
If you just want to plug it in and ride it then you don't need anything at all it looks like. Would probably be worth downloading the manual from the Saris website and reading it for further information.