Cribbed from the pinned post on the Discord channel and input from moosic -thanks!
Download and install the 32-bit version of Basilisk (unfortunately, this is no longer maintained, but it still works)
The latest available installer is http://archive.palemoon.org/basilisk/basilisk-20201125140449.win32.installer.exe
Other versions available here: http://archive.palemoon.org/basilisk/
Install shockwave , either the "download Full EXE installer" or "MSI installer"
even though at the top it says it's discontinued, you are still able to download it.
Adobe download page
When you try to play, make sure that you visit this URL https://isketch.net/isketch.shtml
See this Reddit post
Note that it's probably a really good idea to then go into the Chrome plug-in settings and only allow IE Tab access to https://www.isketch.net/