After downloading the app, you will want to login to see your Hub and the devices attached to it. Upon opening the app, you will be given a couple of options to do so.
The connect button will allow you to connect to the Hub remotely. The Hub and your phone will need Internet connection for this to work, but they don’t have to be on the same network. Another prerequisite is that the Hub has been added to your account.
This login option will only work if the accessing device is physically close to the Hub as it requires both the accessing device and the Hub to communicate on the same Wifi network. This is a good backup solution if you Internet provider is failing at providing Internet connection. Having a router that can still manage Wifi network will allow you to access your Hub and control your devices.
Note that you do not need to have the Hub added to your account to access your Hub locally.