Did you perhaps install FSReaWX Pro into C:\Program File(X86)? Windows, especially Win10, has severe personal problems with permitting editing of anything in that folder, even with UAC turned off. Supposedly.
Also, setting up a plane can be done, but I recall you need to give it the name of the aircraft as seen in the aicraft.cfg file, either the Title= line or the Variation= line. Something like that. I don't recall exactly.
Good luck, in any event. I only use FSRealWX Lite. It seems more stable an reliable as far as providing weather info, in my system. I have Pro installed, and use it ocaisionally, but I prefer Lite. Just a personal thing, I guess.
Pat☺