Yes the description is correct but when u look into the Power Specifications field of the 620 controller datasheet , it is clearly stated "Power Over Ethernet capacity per port : 19.5 watts" which is only 802.3af PoE
If you look at the AP270 series datasheet, you will see that from the ordering information, the PoE midspan injector PD-9001GR-AC is clearly stated 30W.
Could you connect a serial console cable to the AP275 during boot up and see from the boot up log, do you get "insufficient power" ?
To summarize, the 620 is providing 802.3af PoE 19.5W and the AP275 need 802.3at 30W.
Raymond.