GarageBand version 10.0.2. I haven't upgraded since getting this computer because I keep reading nightmare reviews about incompatibility with earlier project formats and more recently in versions 10.1 and 10.2, removal of functionality. Apple appears to be ignoring the negative reviews and pushing ahead with ruining GarageBand in future updates, so I'd like to avoid updating to 10.1 or later.
Most instruments are grayed out. If I click on 1 of them it offers the complete collection for a 1-time purchase.
Except the "Continue" button doesn't work. Clicking it produces a loading spinner over the advertisement offer and then the window closes with no explanation of what happened.
The same thing happens with the purchase button off the main menu.
Best Answer
Apple have made all the instruments free to download. It appears older versions of GarageBand don't understand the server response after this came into effect, and therefore it's not possible to download them without updating to the latest version of GarageBand.
It may be possible to use another computer or virtual machine with a newer version of GarageBand to download them, then copy them to your own computer, but I haven't tested this.