I wanted to attempt this speedrun but since flash is deceased (R.I.P.) I can't play on the website as stated in the rules. I can access it on other websites though. I was wondering if there could be an alternative website for attempting the speedrun or if theres a way to download the game, or something else along those lines.

Click on 'guides' in stick war's speedrun.com page, there will be a guide for running the game using a flash projector