PoE IEEE802.3af Class 3 (<12,95W)
The first datasheet you refer to is the consumer of the power. The device will have another regulator on the board to regulate the voltage into required level. This is same as regulating a external supply from a wall adapter (probably alternate supply Input, not mandatory) .

The second link is the power injector which has the capability to add the Power into the existing LAN to make it PoE LAN.

The PoE will be mentioned only in the terms of maximum power it can deliver. The voltage should be regulated in the receiving final endpoint according to its needs.