I tried to download the collection but it instead of .swf file I got files that said something else
Maybe you try to download it from Google Drive. When you go to livesplit and type in the game Red Ball, there should be a line with "Autosplitter". When you see the line you can click the "Website" Button. This should lead you to google drive
maybe you clicked the wrong link? here i'll link it: https://drive.google.com/file/d/1dvM7VoIdnX9sEo7OB6J7ybNcZG_ZrCpp/
(copied from discord announcement)
The migration of IL runs from Red Ball Category Extensions has been completed. ILs are now hosted on the Level leaderboard of each individual game in the Red Ball series. The RBCE IL board will remain up for a few days until everything has been archived, but no
