This is stated in the description of the article:
"A 5 V power connector allows the use of an optional power supply unit (5 V / 2 A, not included) when connecting devices with high power requirements."
So: The optional power supply is not included (otherwise it wouldn't be optional).
Otherwise, the part draws its power via USB. And I assume you can use any USB power supply.
The USB hub can be used to connect an external USB3 hard disk (tested with a WD 1TB MyPassport) and a USB card reader (tested with Kingston USB3 High-Speed Media Reader (USB 3.0); art. no. 5334803) together on a Surface4 Pro and thus copy the data directly from the smart card to the HDD. I think this should also work with an external SSD, as it requires even less power. The diversions via the internal disk of the Surface or the additional built-in MicroSD of the Surface is therefore NOT necessary. Transfer rate with my "old" 1 TB HDD with a SanDisk Extreme Pro 64 GB (95MB/s): around 32 MB/s