So, I saw that the 25th Anniversary Edition is available on GOG.com and included the Legacy Edition (with ScummVM) as an extra. I went ahead and purchased the 25th Anniversary, downloaded Legacy Edition, and installed it.
Attempting to open the game sends me to a ScummVM screen where I am informed that the game data is missing.
Anyone want to recommend a workaround, or is the 25AE version good enough?
Which version is it you are trying to run? I just tried setup_simon_the_sorcerer_classic_(19666) and it worked fine (both floppy and CD versions). Did you customize the language in any way?