My apologies but I'm confused I d/loaded from the link provided by SimPlanet i.e. cyvr_fsx_setup.exe .
That's the issue. You should have said that the installer didn't recognized your P3D version, NOT that it doesn't proceed after the boxes...
First you should NOT use the download link provided by Sim-planet, because is outdated. You should ALWAYS use the download from our site, because that's the one which is guaranteed to be always updated.
The issue is, many 3rd party ecommerce sites have a limitation that, after you purchase something, you MUST download something, they cannot just present you a link (which should have been on the "Products" page of our site, where all our downloads are found), so they still host the previous release of that file.
We contacted Sim-planet and ask them to fix the problem, or at least (if they cannot just present a link) to let to you download a text file with the link, instead of the actual installer, which might be difficult for them to always keep updated with our version.
About the P3D Migration too, yes, it must be DISABLED when installing and using any addon that recognize P3D natively.