After a moderate struggle I've got this thing installed. To be precise, what was actually shipped to me was "Total Workstation XL Bundle", though SampleTron is what I ordered from Amazon.
I have two issues:
1. The standalone SampleTron thing can't be used with a MIDI keyboard. The keyboard works perfectly with GarageBand. In the preferences, I told it to use the same MIDI input as GB. If I play the little tiny screen keyboard in the UI with the mouse, I hear sounds. They're unusable (no attack or release -- presumably there's a hidden setting somewhere), but at least they're audible.
2. In GarageBand, I create a software instrument and click the "knob" button for settings. Everything I read about this online says to click the "i button". There's no "i button" (I've seen screenshots, and I remember that version of the UI; this isn't it). There's a "Vintage Electric Piano" button, which shows a menu that lets me choose among "AU Generators", "AU Instruments", etc -- but every option under those menus has "Apple" on it. None are IK.
I can click on "Audio FX" and get a menu with an "Audio Units" submenu at the bottom. That submenu has an IK Multimedia submenu full of unintelligibly named options that cause error messages if selected.
IK claims this product works with GarageBand, but I know all about the kinds of things software marketing people say. Is that claim obsolete? What's the return policy?