can't install Ps CC (2015.5) free trial off Creative Cloud

Hi, I'm using a macbook air 2014 running the 10.9.5 OS and when I try and install Photoshope using Creative Cloud it stops at 6% every time and gives me this:

Exit Code: 190

-------------------------------------- Summary --------------------------------------

- 2 fatal error(s), 0 error(s), 0 warnings(s)

FATAL: Sanity check for installation failed. Current OS version 10.9.5 doesn't satisfy OS requirements.

FATAL: Error occurred in install product workflow with error code 190 error message

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When I go on the app store it says my mac's totally updated and it's only 4 years old so surely it should be good enough for the 2015 version of PS right?

Any help would be greatly appreciated.

Thanks,

ceej