Installing 64-bit openHAB2.0 on QNAP TS-251+

I am running firmware version 4.3.2 on my QNAP TS-251+ server. I would like to install openHAB 2.0. I have tried installing the qpkg from the openHAB website, but it’s not opening. I suspect that it’s x86 version. Is there an x64 version out there?