To install custom Android 7 firmware on an Android 5.1 Q5 Pro you must first install an official Android 7 firmware.
So, for Q5 Pro:
* First install official 2.0.1: http://www.futeko.com/newforum/index.php?topic=1610.0
* Then install custom CS 2.0.1: http://www.mediafire.com/file/3fd3e4xp6uv8k06/update_Q5Pro_%28WIPE%26update%26themed%29_HMD-2.0.1_2017-01-11.164329.zip
The installation method is slightly different for each, in that for our official firmware you must extract update.zip from the archive but for the custom firmware you must rename the archive to update.zip.
I agree with HereisTom btw, you may as well stick with Android 5.1 at the moment and update when the next Android 7 firmware is released.