Are you using the stand-alone version or the CC version?
If you can launch Lightroom, from the menu go to:
Help >> System Info
You should see something like this for example:
Lightroom Classic version: 7.1 [ 1234567 ]
License: Creative Cloud
Please reply with the following information
Your version of Lightroom will not run under OS X 10.9.5 (nor will Lightroom version 7.1)
You have to downgrade your Lightroom to 6.6.1, or upgrade your operating system to 10.11 or later.
How do I do that downgrade of lightroom? The CC Application doesn´t show me any possibility to do that.
Build number 1149743
I have the whole CC
But I guess I found my mistake, I thought version 2015.14 was earlier than 2015.6. Interesting though that I was able to install a version that is not compatible with my OS directly from my CC App.