I've got it working (SRV2KI-BR) but used the serial cable (and a serial-usb converter), with the USB it didn't work.
Here is the steps:
1) ONLY CONNECT SERIAL CABLE, don't connect both (usb port) or it won't work.
2) Connect ups to server/pc, you can use a serial-usb converter
3) look the /dev/tty (dmesg will show) in my case: "usb 2-1.3: pl2303 converter now attached to ttyUSB0" so it will be /dev/usbttyUSB0
4) Not sure why default UPS Settings didn't show as connected, it works if I use acptest from cmd, so I tried NUT (install from apps).
5) Settings for USP Settings: UPS cable: smart, UPS type: APCsmart, Device: /dev/usbttyUSB0 (or the one you got from dmesg)
6) Settings for NUT - UPS Driver: (CUSTOM) apsmart, UPS Port: /dev/usbttyUSB0 (or the one you got from dmesg)
7) Profit, after that it worked!