Thanks; that's useful feedback.
Would it help if the first door puzzle gave some more explicit tutorial, complete with pictures?
Something like "It looks like I can click circles to change their colors, and clicking the big blue button here <show arrow> attempts to submit the puzzle. This bottom section <arrow> looks like a button that might appear once I have it correct. It looks like the background color tells me what color a space needs to be.
That should hopefully carry through pretty well to the other door puzzles, and hopefully the non-door puzzle interfaces are straightforward (even if the method for solving them isn't).