As you can see in your screenshot, P3D 5 is not even listed in the possible (and eventually "not found" ) simulator, and that's because you are using a very old installer, one that came out not just before P3D 5, but even before P3D 4.4, since it reads "4.0+" for P3D4, while the current version of our installers supports only P3D 4.4 and 4.5,
Maybe this is the reason why you use an outdated installer is because for some reason you are still using 4.3 ? I strongly suggest to update to AT LEAST 4.4, the difference are massive, since 4.4 is when PBR support came, and all our products, especially GSX, which all sceneries ( surely KMEM ) requires.
The latest installer for KMEM on our site, version 1.65, came out in 2020, and it supports P3D 5.0 but, it requires at least 4.4 in P3D4.
