Please also note the thread for porting it Add OpenWrt support for Ubiquity AirCube ISP (UBNT ACB-ISP). It's now possible to install via web interface too. See the wiki page for that.
@kazigk already asked about the AirCube with 5GHz WLAN (the one without ISP in the name) further down in the other forum thread. My assumption from there is still the same: Most likely the FDT has to be adapted and maybe some calibration data have to be found. Maybe @kazigk has tried something.
I still don't have a 5GHz AirCube and currently I'm very busy with other hobby projects (especially starting a Repair Café). So I won't find any time for that in the near future.