if you click the Purchase button for GarageBand 2.0, does it offer you to install the older version instead? Then try it. If not, there is now no longer a way to get the older version. This is one of the main reasons, why we should update to the newest versions, as soon as they become available. The Mac AppStore is giving us only a small window of opportunity to get the matching software versions of the applications for the current system.
You can get the older GarageBand '11, version 6.0.5 instead. It is still running on Yosemite.
Did your Mac come with iLife Installer disk or a disk with bundled applications? Then try to install garageBand from these disks and update GarageBand to version 6.0.5.
The iLife '11 DVD will probably install an older version of GarageBand '11.
You can update it using this updater: GarageBand 6.0.5
And the installer may be showing a warning about an expired certificate. In that case set the date of your Mac back to the year, when the installer has been released, while you install the software.