I'm not sure which video you watched, but I double-checked the video for Aria Player and SampleTank on the Mac video page ("Using Band-in-a-Box with stand-alone synths") and it indeed does show the Mac BIAB (not the pc) and very clearly shows how to play sounds via Garritan or ST. For SampleTank specifically, you need to enable the IAC driver in Audio MIDI Setup and select that as your BIAB output and your ST input.

http://www.pgmusic.com/bbmac.demos.htm#rtnew


UltraPAK 2021, 27" late 2012 iMac, 16 GB RAM, OSX 10.15.7
Logic Pro X 10.6.3