Posting this reply for anyone else who makes this mistake, I got it figured out, but holy crap I'm dumb and this was all my (not MM's) fault: When installing Garritan sounds it gives you a prompt to...

How is this done?

Yes

I've just gotten v25 for macOS Sierra, and am having problems with playback. I tried to go into Aria to load the sounds myself, but got the attached error message instead. What do I need to do?...

I've tried doing this with the default document to no avail. I want to change the default expression metatool M from Rehearsal Letters to Measure Number, and the master tool shortcuts (⌃J-;) to the...