The XClass installers are made for FSX. They won't install if FSX:SE is installed alongside FSX.They will work if you install FSX:SE stand-alone, which is how most of the FSX-only addons that don't specifically recognize FSX:SE are installed.
Thanks, I have it standalone so I guess it should work. Last question, is the "eCD" product just all of the xclass products in a vundle, but still a download?
I have also installed FSX:SE on fresh Windows, so I assume there will be no problem with installation, but I have now Windows 10 - do I have to expect any problem?