I can't speak for VST plugins since I use a Mac, but any AU Mac plugins will work in Finale. But it also matters what type of plugin are you referring to. A reverb plugin, or equalizer or compressor plugin should work, but if you're referring to Sample library plugins, that's something different. Finale's HP is based on specific programming for the Garritan libraries, you're not guaranteed that it will work with other samples without editing your HP preferences.

I do not know how much help this will be, but I can pull up Steinberg's HALion SE Player (a VST3 Player) in Score Manager and set it to play sounds from the HALion Orchestra set with no perceived problem at all.

Whether HALion has a VST2 backup iteration installed somewhere on my machine that I do not know about, I cannot say; but I doubt that is the case.

Mac—I don't think so but it might depend on the player. Pretty certain that Aria supports AU only on the Mac but that's all I use.

Windows—It depends on the player. I don't know about Aria

Bryan,

On Windows, Finale can use VST and VST2 plug-ins, but not VST3. Audio Units on macOS are different and Finale does support all Audio Unit plug-ins. With either, the use of functionality and features a plug-in offers while using it in Finale may vary depending on what a specific plug-in does or is capable of and how these parameters are designed to be controlled.