Hi Mike, welcome to the forum.
The sound set XML file needs to go into the Sibelius "Users" folder. Since you're on a Mac, that would be:
Macintosh HD > Users > youruserneme > Library > Application Support > Avid > Sibelius 7 > Sounds
If the "Sounds" folder is not there, you'll need to create it.
The sound set XML file needs to go into the Sibelius "Users" folder. Since you're on a Mac, that would be:
Macintosh HD > Users > youruserneme > Library > Application Support > Avid > Sibelius 7 > Sounds
If the "Sounds" folder is not there, you'll need to create it.