Thank you, Andrew!
If you ran the installer, you should find it on your Mac hard drive in the Applications\Band-in-a-Box folder, the same location as you find it on the USB drive.
I did run the installer. There is a Band-in-a-box folder in my Applications folder. Inside the Band-in-a-box folder, I see three folders: Drums, Plugin Settings and RealTracks. There's no sign of a Band-in-a-Box application. Are other files or folders also missing?
I would just do a search for "Band-in-a-Box" and that should find it quick.
Did that. No application on my internal hard disk. Apparently, I either did something wrong, or the installer made a mistake. I suppose I might just trash all those files and try the installer again. Is that what you suggest?
If I made a mistake, what do you think I did wrong? Any way to prevent similar problems next time?
Edit - later on: I trashed those files and folders, ran the installer again. It worked this time. I'm not sure what went wrong the first time, but I guess it's not important now. Thanks anyway.