I use my 27" iMac (late 2013) using OS 10.13.1 and Finale 25.5.0.259 to arrange for a small band.  I play back on a Yamaha PSR-E443 keyboard using a USB connector.

I recently purchased and installed Garritan Jazz and Big Band 3.  I can see and hear that it is working on Internal Audio, but when I select "... through Midi" the sound is just like it was before my purchase.  Is there a way for me to get the Jazz and Big Band 3 voices to play through my keyboard?