Once you manually add the Virtual Pushover Device, and configure its settings, it will show up as a Notification device in any Apps that support sending a notification. The Hubitat Mobile Phone App also creates a Notification device on your hub which also can be used to receive push notifications. The nice thing about Hubitat, is that is doesn't matter which 'notification' method you choose, they all end up as a simple device that you can select.
If you have multiple users in your home, you can create a Pushover device on your hub for each of these users. Installing Pushover on their phones, and using your same Pushover credentials on every device, will allow you to configure each Pushover Device on Hubitat with a single user's device.
For more info on Pushover, take a look through the following thread...
