Same issue as previous game (Hometown Hero) which can also be fixed, but adds upon the frustrating mechanics of the Seasonal Pack
It wasn't until Adobe blocked support for Flash in 2021 that it revealed the reason this didn't work post MacOS 10.9 Mavericks; the beginning of new area cutscenes. This can be fixed by doing the following.
1. Go to Finder and find Diner Dash: Flo Through Time in your Applications section or in a folder for MacGameStore. Right click the icon and click 'show package contents.'
2. The folder you're looking for is hidden for security reasons. First click on the Contents folder then resources and enter on the keyboard at the same time Command+Shift+. (the period key.) You'll see a lone new folder called 'Game.'
3. You'll find the base game which has all the info for the game to run. Like last time, right click. 'show package contents,' and go into contents. Now go to resources, assets, downloads, _default, and restaurants.
4. Each folder are the locations in the game; all of them have one folder called 'Comics' with a .swf file. You can either outright delete the folders or just the files themselves.
5. The only issue you'll have now is during the loadup with the same 'missing plugin' - I'm sure there's another file you can delete to outright skip it, but you can just click anywhere to skip it (it's probably just the game company logo.)
When you get into the game, there's a mechanic where you have to give attention to a creature (in the first area, it's a dinosaur.) If you don't give it attention, it will have a temper tantrum until they're comforted. Frankly, PlayFirst seemed to be trying too much to 'freshen' the time management formula and in doing so, got rid of the fun factor - getting more comfortable you play, the game gets harder.