Hi!
This happens with any .rar file you download from the web, if you don't save the .rar file to a location of your choosing but instead choose to just open the .rar file when it has finished downloading. Then the default destination path for extraction is C:\Users\YourUsername\AppData\Local\Temp\Archipelago.
But if you choose to save the file instead of opening it, then it goes to your downloads folder (default is C:\Users\YourUsername\Downloads) and when you then extract the files, the default path is C:\Users\user\Downloads\Archipelago.
From there on you still need to extract the actual game from the Archipelago.exe file with blue icon. This is an unnecessary step which I could've avoided, but I pretty much just copied the process from an igmc 2017 entry which had success in the competition.
Hopefully this clears things up a bit :) But if someone has problems just hit me up and I'll be more than happy to help out!