Can you download and install Premiere Elements 14 Mac or install Premiere Elements 14 Mac from installation disc to your Mac OSX 10.8.5?
The Adobe System Requirements often reflect what Adobe has tested and consequently steps forward with a support statement. That does not necessary mean that a version will not work on a particular operating system. There is at least one user who writes that Premiere Elements 14 and 13 are working on Mac OSX 10.11 which is not in the Premiere Elements 14 Mac or Premiere Elements 13 Mac System Requirements.
Based on history, if you contact Adobe, my first impression would be that it would tell you Mac OSX 10.8.5 does not support Premiere Elements 14 Mac. Have you been there and done that and gotten that reply?
The answer to the initial question is significant in deciding what next.
Is there a reason you're not only at least Yosemite, if not El Capitan? The OSX upgrades are free -- and, since they're all just variations of OSX, it's rare that software that works on one version won't work on the next generation.
Virtually any Intel-based Mac is capable of running the latest OSX, which is faster and more efficient than previous OSXes.
There is at least one thread in the Adobe Photoshop Elements Forum dealing with problems of MacOSX 10.11 and Photoshop Elements.
You might want to check out the specialized expertise there on this matter. Here there is at least one thread where the user is working with Premiere Elements 13/13.1 Mac and 14 Mac on Mac OSX 10.11 without issue.
But, still would like to know if you could or could not install Photoshop Elements 14 Mac and Premiere Elements 14 Mac on Mac OSX 10.11.