I have no idea how you just skipped over the section labeled "RMRK Game Creation" and went past it to a random section that's described as "Talk about almost anything that isn't covered by any of the other forums," implying that you should look at all the other boards first and see where it would best apply. Especially if you can recognize that this is probably the wrong board to put it in.
In any case, said, the RTP is what you need to play most/all games. If there's any custom resource, it'll probably be included. Sometimes you won't even need the RTP since some people may have versions where they include it.
As for the illegal download, you should be fine using it. Nobody will track you down unless you actually use it for commercial use. In that case, you're better off just buying the program. Of course, if you're planning to make a game for commercial use, you're better off just learning to code on your own.