Powering Vizy is typically done by plugging in the AC-DC power adapter that comes with Vizy into Vizy's power input connector. The power adapter supplies 12V at 2.5A.
The PoE adapter is a popular way to power Vizy as well. But Vizy can be powered by other means as well.
You can power Vizy with a 5V supply through the USB-C connector. This is useful if you want to use a portable charger to power Vizy via battery. (Portable chargers output 5V through a USB port and typically have a large battery capacity.)
You can also power Vizy through the I/O connector, which can be convenient since the I/O connector terminal blocks are easy to use. The disadvantage is that you lose the 12V output for the time being (the 12V output is designed to also be a power input.) To power Vizy through the I/O connector hook the negative side of the supply to one of the Ground pins (pin 1 or 8) and the positive side to the 12V output (pin 2). The same conditions apply to this method as apply to powering Vizy through the power input connector, including reverse-polarity protection.
For example, if you have a 12V battery, you can easily wire it into Vizy's I/O connector and be up and running quickly.